WASHINGTON — President Trump has framed the first general election debate as a test for his opponent, former Vice President Joseph R. Biden Jr.
Yet he has simultaneously set the bar so low for so long that many of his supporters — having watched unflattering, often manipulated clips of Mr. Biden in Trump campaign advertisements or on Fox News — are now expecting the president to mop the floor with an incoherent opponent in something resembling a W.W.E. match.
Democrats — and even some Republicans — believe that is not likely to happen.
The misleading notion that Mr. Biden is too addled for the presidency has been driven by Mr. Trump since 2018, when he first started referring to the former vice president as Sleepy Joe. Since then, in speeches, in interviews and at his rallies, Mr. Trump has been crafting a narrative depicting the former vice president as having a diminished physical and mental stature, in the hope of making voters believe that Mr. Biden is unfit for office.
It is a message that Mr. Trump’s campaign has spent millions of dollars amplifying, often in misleading, spliced-together clips contrasting an energetic Mr. Biden from the past with a supposedly barely functioning one now. And the campaign has posed the question to voters: “Did something happen to Joe Biden?”
“It’s an uncomfortable conversation to have, but voters deserve to be able to assess Joe Biden’s capabilities by seeing him and listening to him in his own words, especially as compared to just a few years ago,” Tim Murtaugh, the Trump campaign communications director, tweeted.
Most recently, the president floated the baseless conjecture that Mr. Biden was on performance-enhancing drugs. Trump allies have taken the talking point even further. Representative Joe Murphy of North Carolina claimed outright last month that Mr. Biden suffered from dementia.
All of that means that if Mr. Biden does not appear weak, the tactic will have backfired.
Brett O’Donnell, a Republican strategist who has coached candidates ahead of debates, said the Trump campaign might have given Mr. Biden an unintentional gift.
“In trying to message that Biden may be unfit for office, the campaign also may have lowered expectations on his debate performance,” Mr. O’Donnell said.
Studying Mr. Biden’s various debate performances, the president’s advisers began warning Mr. Trump months ago that the former vice president had successfully handled a lengthy, one-on-one debate with Senator Bernie Sanders in March toward the end of their primary fight. Outside advisers warned Mr. Trump that he needed to change the way he was playing the expectations game with Mr. Biden.
So Mr. Trump has tried modifying his approach in his public comments, grudgingly acknowledging that Mr. Biden fared well in the two-man debate.
Given that Mr. Biden’s performance may exceed the low expectations that the president has set, Mr. Trump on Sunday morning threw out the wild suggestion of a “drug test” before or after the debate. “Only drugs could have caused this discrepancy” in Mr. Biden’s debate performances, Mr. Trump tweeted, claiming the former vice president’s debates were “UNEVEN, to put it mildly.”
Mr. Trump has not been able to stop pointing out where Mr. Biden struggled in more crowded primary debates. And the stage-setting has been years in the making.
“There’s talk about Joe Biden, Sleepy Joe, getting into the race,” Mr. Trump said at the Gridiron Dinner in 2018. “Just trust me, I would kick his ass.”
In March 2018, after Mr. Biden said he would beat up Mr. Trump if the two were still in high school (a comment he later apologized for), Mr. Trump tweeted that the former vice president was “weak, both mentally and physically” and claimed, “He doesn’t know me, but he would go down fast and hard, crying all the way.”
Mr. Trump began to focus more on the mental deficiencies during the Democratic primary last year. “I’d rather run against, I think, Biden than anybody,” Mr. Trump said. “I think he’s the weakest mentally.”
The president has often engaged in projection, accusing his political opponents of the same charges they make against him. Mr. Biden’s case has been no different. As he has tried to portray Mr. Biden as old and senile, Mr. Trump has simultaneously defended his own ability to drink water from a glass without assistance and confidently walk down a ramp. Groups supporting Mr. Biden have posted clips of Mr. Trump slurring his words or speaking incoherently.
In recent weeks, as Mr. Biden has pulled down his campaign schedule to spend time in debate prep sessions in Delaware, Mr. Trump has practiced mostly on the go. He and his campaign aides have discussed how to raise the most uncomfortable issues for Mr. Biden, like the sexual assault allegations made against him by Tara Reade, even casually discussing bringing her to the debate, and personal attacks about Mr. Biden’s son Hunter.
His aides have compiled for him a 30-page binder filled with bullet points. Instead of regular, formal sessions, aides traveling with him to rallies or official events have used time on the plane to pepper him with questions.
He has had a few meetings in the Oval Office, where he has talked through the debate with advisers and aides, including former Gov. Chris Christie of New Jersey and his advisers Hope Hicks, Jason Miller and Stephen Miller, as well as his campaign manager, Bill Stepien, according to several people familiar with the get-togethers. At least one more prep session was expected to take place over the weekend.
Mr. Trump has never favored formal debate prep with mock-ups at lecterns and instead, in 2016, preferred to tell war stories and vent about what was on his mind. His opponent that year, Hillary Clinton, received a bump in the polls after each of the three debates.
But Mrs. Clinton was known as a strong debater. Mr. Biden — even if he is not what the Trumpian caricature would like him to be — suffered from some very rocky debate moments in the Democratic primary last year and could encounter them again. Mr. Biden regularly cut himself off before his allotted time for speaking was up, making it sound as if he was having trouble finishing his thought. He sometimes says the opposite of what he means.
“I would eliminate the capital gains tax — I would raise the capital gains tax,” he said in a debate last year.
Karl Rove, who served as President George W. Bush’s chief strategist and has informally offered advice to the president and his campaign, conceded that lowering expectations for Mr. Biden was “maybe” an unintentional gift.
But he said Mr. Biden had bigger issues to overcome than simply exceeding that low bar. “What I’m seeing in these battleground Senate polls is that people know that Joe Biden was Obama’s vice president, and that he’s been around for a long time. They don’t really know the guy,” he said. “The Biden voter is simply an anti-Trump voter. What if he fails to make this about what he’s for and what he’s about?”
The Biden campaign, meanwhile, has been telling people that no debate outcome will fundamentally change the contours of a race that has been defined, since March, by the president’s handling of the pandemic, even if the president performs well onstage. Mr. Biden’s hope on Tuesday night, according to someone familiar with the campaign’s strategy, is to continue making the election about the president’s accountability for the lives lost to the coronavirus, while trying to show what it would look like to have a leader in charge who doesn’t need to be fact-checked in real time, and who attempts to bring the country together.
Democrats are concerned that Mr. Trump may be successful at making Mr. Biden lose his temper by talking about Hunter Biden. The president has repeatedly talked about the younger Mr. Biden in the past week, and Republicans have tried to push negative coverage about him in the news media.
In the past, Mr. Biden has struggled to come up with a definitive response to questions about his son’s work overseas and whether it raised questions about conflicts of interest while his father was in office. While Mr. Biden’s empathy and his love for his children have been calling cards for voters who like him, they have made it challenging for him to put those questions to rest.
Mr. Rove accused him of trying to “defend the indefensible.”
But it’s not clear that simply unsettling Mr. Biden with murky accusations of corruption will necessarily have the intended effect on the audience watching at home. “Trump has to try and change public perceptions of him,” said David Axelrod, a former top adviser to President Barack Obama. “That is not going to do it.”
Mr. Trump’s allies are also concerned that the president, who is generally cocooned from people who oppose him, will be unable to resist the temptation to defend himself from Mr. Biden’s face-to-face criticisms.
Mr. O’Donnell anticipated that Mr. Trump would “try to put pressure” on Mr. Biden, through tactics like interruption, name-calling and a physically dominating presence onstage.
“No one has figured out how to debate the president, because he’s so unconventional,” Mr. O’Donnell said. “Because moderators never call him out for doing any of those things, the candidates can’t do it” either.
Still, Democrats said the person who needed a reset was not Mr. Biden.
“The pressure has shifted to Trump,” Mr. Axelrod said. “We’re late in the race; people are already voting. Biden’s lead has been seven to eight points. This is his last best chance to shake up the dynamic.”