With Donald J. Trump rapidly closing in on the Republican presidential nomination, the 2024 general election campaign is set to be one of the longest in modern history, pushing President Biden and Mr. Trump into unfamiliar territory as they struggle to engage an electorate that seems numbed by the prospect of a 2020 rematch.
For all their experience in presidential politics, Mr. Biden and Mr. Trump face extraordinarily complicated challenges as they and their aides grapple with how to run a presidential campaign that will last almost nine months, significantly longer than most general election contests.
This is a race that has been run before, a rematch between two older and by now well-known candidates: Mr. Trump is 77, and Mr. Biden is 81. Mr. Trump has essentially been a candidate for re-election since his defeat four years ago and may spend much of the spring fighting felony charges in court. Both men are unpopular with large numbers of voters.
“What can they possibly say about their opponent that voters don’t already know?” said Mark McKinnon, who was the chief media adviser to George W. Bush for his 2000 and 2004 campaigns.
The time between the end of the primaries and the party conventions usually brings a lull in the campaign, when presumptive nominees test attacks on opponents, shore up their shortcomings and build the policy, political and financing foundation for the fall campaign. That period usually begins in late spring, but if Mr. Trump maintains his commanding lead over Nikki Haley, the former ambassador to the United Nations, it could start before winter is through.
As a result, the Biden and Trump campaigns face a series of unusual strategic decisions in the weeks ahead: How much of the next nine months do they devote to sending Mr. Trump and Mr. Biden across the country for rallies? Is it better to deploy attacks on opponents now, or wait until the conventions, when more voters will presumably be paying attention?
Does nonstop television advertising lose its potency over nine months? And given the unfavorable views of both men, should they limit their public appearances and let the campaign be carried by surrogates and advertisements?
Strategic decisions and missteps made now could prove critical come November. particularly in this contest, with polls suggesting a down-to-the-wire contest between two polarizing and combative candidates.
“I don’t think there’s much of a chance for anybody to sit back,” said Gail Gitcho, a senior adviser to Mitt Romney, the Republican presidential candidate in 2012. “We have seen how close it is.”
The Republican National Convention, where the party will officially nominate its candidate for president, is scheduled for July 18 in Milwaukee; the Democratic National Convention follows on Aug. 22 in Chicago.
Ms. Haley has resisted pressure from Republican leaders to withdraw after her losses in Iowa and New Hampshire. She has pledged to keep running at least through the primary on Feb. 24 in South Carolina, her home state. Both Mr. Trump and Mr. Biden declared the Republican contest over after Mr. Trump defeated her by 11 points on Tuesday in New Hampshire.
No matter what Ms. Haley does, the general election is already fully engaged, marked by an escalated daily back-and-forth between the Trump and Biden campaigns. Mr. Trump and Vice President Kamala Harris both campaigned this weekend in Las Vegas.
“The attacks are going to go on and on and on,” said Tony Coelho, a former member of Congress who was chairman of the 2000 presidential campaign of Al Gore, a Democrat who was then the vice president. “The question is whether the public turns off, or turns on, one or the other candidate.”
The effective start of the general election will complicate any effort by Mr. Biden to remain above the political fray and present himself as president rather than as a candidate. But this new phase of the 2024 campaign means the race is clearly a choice between Mr. Trump and Mr. Biden, the contrast that the Biden campaign has presented as key to its hopes for victory.
Mr. Biden’s aides said on Friday that they would press the president’s message from now through Election Day. The campaign is “focused on innovative efforts to reach voters through organizing and digital platforms, a historic paid media program and an aggressive travel schedule,” said Kevin Munoz, the campaign spokesman.
Jason Miller, a senior Trump campaign adviser, said the campaign would focus on key voting groups in the handful of battleground states, including Latino voters in Nevada.
“From our campaign’s side of things we have always been focused on Biden,” Mr. Miller said.
There was a time when candidates could use a post-primary pause to relax. Senator Bob Dole of Kansas, after capturing the Republican nomination in March 1996 and before running in the general election against President Bill Clinton, flew to his Florida vacation retreat to do, well, not much. (“I’ve got to go up there and eat a sandwich,” Mr. Dole said as he lounged by the pool, gesturing to his 12th-floor condominium.)
But the risks of disappearing during this period are high. Over the past 25 years, campaigns have used any hiatus between the primary and general election to begin attacks to undercut and define their opponent.
President George W. Bush, the Republican, rolled out advertisements in the spring of 2004 that portrayed his opponent, Senator John Kerry of Massachusetts, as a flip-flopper on national security issues. “We absolutely took advantage of the preconvention time period to frame Kerry as inconsistent, wishy-washy and having no real core convictions,” Mr. McKinnon said.
Douglas P. Sosnik, a senior counselor to Mr. Clinton, described that as the decisive moment of the 2004 campaign. “They dropped that bomb on him,” Mr. Sosnik said. “The whole narrative frame of that campaign was decided at the start of the year.”
President Barack Obama’s re-election campaign in 2012 might have effectively claimed victory in the spring, with advertisements that portrayed his Republican opponent, Mr. Romney, a former governor of Massachusetts, as wealthy and out of touch.
To do so, the Obama campaign took money it had set aside for the fall campaign and began spending it in the spring. “We ended up defining him before they ever tried to define him,” said David Axelrod, Mr. Obama’s chief strategist.
Both Ms. Gitcho and Mr. Axelrod said the 2012 campaign, which Mr. Romney lost, offered a lesson for Mr. Trump and Mr. Biden.
“If there’s a vacuum, someone is going to fill it,” said Mr. Axelrod, who has repeatedly criticized how Mr. Biden has run his campaign to date. “You’re in an active campaign now.”
For Mr. Biden and Mr. Trump, there is little in history to draw from in answering the what-now questions they are facing today about campaign advertisements, candidate deployment and the use and the timing of attacks.
“There is nothing quite like this that we have been through,” said Bob Shrum, who was a senior adviser to Mr. Kerry and Mr. Gore. “It’s going to be a campaign unlike any we’ve ever seen.”
Given the uncertainty of this moment, veterans of past political campaigns said Mr. Trump and Mr. Biden should take advantage of their ample financial resources and press ahead to build up their support, no matter the risks of further saturating the attention spans of voters already weary of another Biden-Trump face-off.
Mr. Sosnik said the White House should be sending Mr. Biden around the country now, to generate enthusiasm among Democratic base voters who might have drifted away from his coalition over these past four years.
“I would be working on boosting my numbers, and I’d be going for the lowest-hanging fruit, which is the base,” he said. “I’d put him out in small rooms where there’s energy and enthusiasm. Create events and moment.”
Ms. Gitcho said that given the closeness of the race, the former president should escalate his attacks on Mr. Biden. “Trump should be on offense and on the road and try to define Biden.”
That said, Mr. Trump’s various legal cases have already taken him off the campaign trail, although he has used his court appearances as an extension of his campaign. On Friday, a jury ordered him to pay $83.3 million to the writer E. Jean Carroll for defaming her before and after he was found liable of sexually abusing her.
Mr. Trump has never been known for exercising self-discipline as a candidate, and even after declaring the Republican primary resolved, he has continued his attacks on Ms. Haley, mixing them up with his attacks on the man he may be running against in the fall.
Still, as unconventional as Mr. Trump has been as a candidate, he has in some ways followed a traditional playbook in making the transition from the primary, settling on his lines of attack on Mr. Biden, clearing the field of opponents and uniting the party behind him.
“Trump has already pivoted to the general election,” said Scott Reed, who managed Mr. Dole’s campaign in 1996. “He has grabbed hold of the congressional Republican leadership and set the terms of the general election.”
Michael Gold contributed reporting from Las Vegas.