Biden's campaign has invested heavily in emotional swing-state television advertisements that tie Trump to the 2022 Supreme Court decision overturning the constitutional right to abortion with the stark concluding tagline: “Donald Trump did this.”

Now, Biden's team is escalating its efforts to contrast his record against some of Trump's other controversial initiatives. An ad aimed at Black voters that the campaign released Tuesday, for instance, juxtaposes Trump's attempt to repeal the Affordable Care Act with Biden policies that have expanded coverage, lowered premiums under the law and capped the price of insulin at $35 per month. “Trump was a failure on health care,” a narrator declares, before a Black woman in the ad says: “We cannot go back.”

Michael Tyler, the Biden campaign's communications director, said more of those messages are coming. “This is exactly why you run a campaign,” Tyler said. “As we move forward here, reminding people of the damage he caused, the damage he will cause and how he made you feel every single day is imperative.”

Almost every president sees their retrospective approval ratings improve after they leave office; when Gallup last measured views of former presidents in 2023, each one it included except for Bill Clinton received a higher approval rating than when they left the White House. Even Jimmy Carter and George H.W. Bush, the previous two one-term presidents before Trump, were each much more popular in the poll than when they lost their reelection bids. Trump's recovery since leaving office is “not a completely new phenomenon,” said Emory University political scientist Alan Abramowitz, who specializes in studying presidential approval.

In Gallup's poll last year, Trump's retrospective approval rating stood at 46%. That was up 12 percentage points from his final approval rating in office of 34%. Trump's improvement in the Gallup poll since leaving office was about the same experienced by both Carter and George W. Bush in their first Gallup post-presidential assessments.

Other surveys suggest the backward-looking judgments on Trump have further improved since then. In an April national New York Times/Siena College survey, for instance, slightly more registered voters (48%) now say Trump left the country better off than worse off (46%) after his presidency.

Nearly two-thirds of voters in the April New York Times/Siena survey said they approved of how Trump handled the economy and about half said they approved of his handling of both immigration and crime.

The April national CNN survey conducted by SRSS reported some of the most dramatic change in attitudes. From the 2021 CNN survey until last month's poll, the share of people who termed Trump's presidency a success increased more for women than for men; more for people of color than for White voters; more among working-age adults than seniors; and more among Democratic voters than Republican. The 55% in the recent CNN poll who termed Trump's presidency a success far exceeded the 39% who gave the same positive verdict to Biden's time.

Abramowitz, the political scientist, said that in today's highly polarized political atmosphere, it's not surprising that discontent with Biden is boosting Trump, almost in hydraulic fashion. “There's always going to be an inverse relationship to some extent in how people assess the current president of one party versus the previous president of the opposite party, but given that partisan loyalties are stronger today, that is probably a stronger tendency now,” Abramowitz said. “If you are unhappy with how things are going now, that may influence your assessment of the previous presidency.”

Republican strategist Brad Todd likewise said that Trump, in effect, looks bigger to many voters because Biden looks smaller. “We judge presidential approval by strength and success more than anything,” Todd said. “People think the economy was better when Trump was president, whether they liked him or not, and they think Trump projected strength rather than weakness, and plenty of voters find aspects of Biden's presidency weak.”

The Biden comparison also could be benefiting Trump in a more specific way: by encouraging voters to shift the issues around which they are judging Trump's tenure. Because inflation, as well as immigration and crime, are much more relevant to voters today, in their retrospective judgments about Trump's record they may be focusing more on those issues and less on other elements of his presidency that disturbed them at the time, such as his open use of racist language or the general atmosphere of chaos that surrounded his presidency, strategists in both parties said.

Jim McLaughlin, a pollster for Trump, pointed mostly to shifting public concerns and the contrast with Biden to explain these post-presidential gains for the former president.

When the exit polls conducted by Edison Research for a consortium of media organizations including CNN asked voters what issue was most important to their decision in 2020, McLaughlin noted, the survey didn't include either the cost of living or immigration as a specific choice. That omission, he said, measured how little concern there was in the country at the time about each problem.

Now, both of those issues routinely poll near the top of voters' worries in 2024, with Biden receiving some of his weakest marks on each. To many voters, said McLaughlin, Trump “looks better and better on these issues compared to Joe Biden's failures.”

Many Democratic pollsters say that shift in emphasis about Trump is particularly evident among Black and Latinx voters, especially younger to middle-aged men. “Particularly among working-class Latinx. … They will tell us that they think he's racist, xenophobic, anti-immigrant, anti-Latinx,” said Ben Tulchin, who served as the principal pollster for Sen. Bernie Sanders' two Democratic presidential campaigns. “But then they say, ‘Comma but,' and the ‘but' is they view his economic record more favorably than Biden's. Maybe through rose-colored glasses, but that is a challenge the Biden campaign has.”

In that New York Times/Siena survey last month, for example, 70% of Latinx voters said they disapproved of how Biden is handling the economy, while 74% approved of how Trump did.

Democrats acknowledge that while it is important for Biden to improve views about his own economic record, it may be difficult for him to tarnish the positive impressions most voters hold about the economy under Trump — at least before the Covid-19 pandemic struck in 2020. “I don't know if it's possible to impeach the state of the economy under Trump,” said Campbell. It will not be easy, he added, to say to voters, “‘Well, your memory is wrong, things were not that great in the economy under the previous guy.' I just don't think that will get them very far.”

Rather than trying to erase positive views on Trump's economic performance, Campbell and other Democrats think Biden could have more success reminding voters about everything else they didn't like about his time in office. “Economy aside, you can't let people think the rest of life was hunky-dory under Donald Trump, because it wasn't,” Campbell said. “His approval never got above 50% for a reason. There is plenty to dislike there and plenty that people did dislike.”

In fact, while Trump was president, polls underscored the dynamic Campbell describes. In that final CNN/SRSS poll in 2021 before Trump left office, a majority of Americans said they approved of his handling of the economy, but even so, 55% described his presidency as a failure, and just 26% said he had changed the country for the better.

The challenge for Democrats, Tulchin said, is that while current conditions are constantly reminding voters that staples like gas, groceries and rent cost less under Trump, the controversies he ignites tend to burn out faster. “What we have seen with eight or nine years of life with Trump as a presidential candidate is unless the glaring awful things he does are right in people's faces — January 6, ‘good people on both sides' post-Charlottesville, kids in cages — then two weeks later, it fades away,” he said. “You've got to force people to watch the horrific person that Trump is. They can't look fondly back on five years ago by overlooking his character flaws, because they are major.”

The new Biden ad aimed at Black voters released Tuesday may encapsulate the campaign's emerging approach to talking about Trump's record. The ad takes one of the most controversial episodes of Trump's presidency — his attempt to repeal the ACA — and uses it to create a point of comparison with Biden's policy initiatives to expand access to health care and to lower medical costs. The same approach is evident in a new Biden ad aimed at Latinx voters that contrasts the former president's policy of separating migrant children from their parents at the border with Biden's efforts to reunite the families.

Another example of that strategy was evident when Biden last week visited Racine, Wisconsin, where Trump had gone as president to trumpet a $10 billion investment from the Taiwanese electronics manufacturer Foxconn, which never materialized. Biden was there to tout a $3.3 billion Microsoft investment in an artificial intelligence center on the site, which he offered as evidence for the success of his broader agenda to promote private-sector investment in advanced industries such as clean energy and semiconductors.

“Folks, during the previous administration, my predecessor made promises which he broke more than kept and left a lot of people behind in communities like Racine,” Biden declared. “On my watch, we make promises and we keep promises. And we leave no one behind.”

Biden's campaign expresses optimism that by reminding Americans about Trump's record on these fronts it can move voters — particularly in core constituencies that have drifted toward Trump such as younger Black and Latinx men. Trump's standing with some of these groups may wilt, these Democrats think, simply as he spends more time back in the spotlight.

But Todd, like many Republicans, believes Democrats are wrong to assume that more exposure inevitably means less support for Trump. “Democratic strategists … have been saying that for a year now,” Todd said. “I think it's time to reevaluate that geometry.”

Refreshing voters about Trump's prior record could add weight to all of Biden's warnings about his future plans. Reminding college-educated voters about Trump's record on abortion and January 6, for instance, could heighten their concern about how basic rights and democracy itself would fare in a second Trump term. Likewise, recalling for Latinx Trump's family separation policy may add credibility to Democratic warnings about his plans to undertake a mass deportation program of undocumented immigrants, complete with internment camps. If Trump is convicted in his New York hush money trial, in which he's pleaded not guilty, it will remind voters not only about his willingness to push the boundaries of law and morality, but also the volatility that perpetually envelops him.

What's less clear is whether enough voters will make their decisions in November based on those concerns as opposed to the issues where polls show they now express more faith in Trump than Biden, such as inflation, the border and crime. In the end, what voters remember about Trump's presidency may be less important than what they prioritize. The real risk for Democrats is that Biden's present may have irrevocably changed what swing voters care most about in Trump's past.

Mr Kretinsky has agreed to make contractual undertakings to the Government to protect key public interest matters. These include maintaining Saturday deliveries for first class letters and keeping the one-price-goes-anywhere service.

The tycoon, who is known as the “Czech sphinx” in the City, has also vowed to maintain employees' current rights, protect the Royal Mail brand and keep the company's headquarters and tax base in the UK.

The board is also seeking assurances that Mr Kretinsky will maintain IDS's investment grade credit rating.

However, the announcement did not spell out a promise to keep the group's profitable parcels business, GLS, combined with its struggling letters division.

Mr Kretinsky's swoop has sparked speculation that the billionaire could look to merge GLS with Dutch operator PostNL, in which he also holds a major stake.

PostNL, which delivers parcels and letters across Belgium, the Netherlands and Luxembourg, is locked in similar debates to Royal Mail about relaxing its commitments on letter deliveries.

Analysts have said a merger could deliver “synergies” across the businesses and improve services for customers.

A source close to EP Group insisted Mr Kretinsky did not intend to break up IDS and said the list of undertakings was not exhaustive.

It is not yet clear whether the commitments would be legally binding.

Any failure to secure legally binding undertakings would raise the risk that Mr Kretinsky could renege on the pledges in future.

In 2010, US food giant Kraft, now known as Mondelez, came under fire for breaking its pledge to keep Cadbury's Somerset factory open. The promise was made during a hostile £11.6bn takeover of the chocolate brand but the factory was closed a year after the deal closed with the loss of around 1,000 jobs.

SoftBank agreed to legally-binding commitments on jobs following its takeover of British chipmaker Arm in 2016. However, these undertakings expired after five years and the Japanese conglomerate subsequently cut hundreds of roles.

Royal Mail said it will continue to hold discussions with EP Group over the scope and duration of the undertakings, which would be made to ministers as well as to the company.

Keith Williams, chairman of IDS, said Mr Kretinsky's commitments “should ensure that IDS continues to deliver the key elements of the universal service in the UK and protect the interests of the workforce at both Royal Mail and GLS.”

The two companies will now start to carry out due diligence, though bosses warned there was no certainty that a firm offer will be made.

Mr Williams said: “The board is minded to recommend this offer price, which it considers to be fair and reflects the value of GLS' current growth plans and the progress being made on change at Royal Mail to adapt the business to a significant fall in the demand for letters and growth in parcels.”

Redwheel, one of IDS's largest investors, previously supported the board's decision to reject Mr Kretinsky's initial takeover bid.

It has argued that GLS alone is worth 350p per share, meaning that under the terms of the improved bid Royal Mail would be worth just 20p per share – or £192m – not even big enough to get into the FTSE 350.

Shares in IDS surged as much as 20pc to 327p following the revised offer proposal, which came just three hours before a deadline imposed under City takeover rules.

Mr Kretinsky, who is also an investor in West Ham Football Club and Sainsbury's, is already the largest shareholder in IDS with a stake of more than 27pc.

His swoop has proven controversial given the sensitive nature of the postal service.

Sir Vince Cable, who oversaw the privatisation of Royal Mail in 2013, has called on ministers to carry out a fit and proper person test on Mr Kretinsky.

The Czech sphinx was previously subject to a national security investigation when he increased his stake in the company above 25pc in 2022, though this was ultimately approved.

A government spokesman said: “We recognise the importance of the Royal Mail to the British public, and we are monitoring these developments very closely.

“Our priority is to ensure that Royal Mail customers get the service they deserve, including six days-a-week deliveries and a guaranteed standardised price for post throughout the UK, as enshrined by the universal service obligations, regardless of the owner.

“We will engage with the bidder at an appropriate time to explain our expectations for the future of Royal Mail.”

In a letter to Mr Kretinsky on Wednesday, Jonathan Reynolds, the shadow business secretary, asked the tycoon to confirm that Royal Mail would remain headquartered and tax resident in the UK, as well as calling for guarantees around postal workers' rights.

He wrote: “Whilst it's important that Britain remains open and attractive to foreign investment, Royal Mail is an iconic British institution with a unique place in our society and infrastructure.

“Royal Mail is as British as it gets, and Labour will take the necessary steps to safeguard its undeniable identity and place in public life.”

The Czech tycoon is also facing opposition from the Communication Workers Union (CWU), which represents around 115,000 postal workers.

In a statement on Wednesday, Dave Ward, the CWU general secretary said: “It cannot be right that a key part of national infrastructure is allowed to be owned by individuals or companies who have no vision for the future and no clear plan to put the workforce at the heart of turning Royal Mail around.”

Mr Ward accused the company's board of trying to “run letter deliveries into the ground and become just another glorified parcels company.”

EP Group's revised offer consists of 360p per share in cash, plus a final dividend of 2p expected to be paid in September and a special dividend of 8p which would be paid on completion of the deal.

EP Group declined to comment.