The former president spoke on Saturday to the North Carolina Republican convention as he resumes political speeches and rallies.

GREENVILLE, N.C. — Donald J. Trump, the former president of the United States, commutes to New York City from his New Jersey golf club to work out of his office in Trump Tower at least once a week, slipping in and out of Manhattan without attracting much attention.

The place isn’t as he left it. Many of his longtime employees are gone. So are most of the family members who once worked there with him and some of the fixtures of the place, like his former lawyer Michael D. Cohen, who have since turned on him. Mr. Trump works there, mostly alone, with two assistants and a few body men.

His political operation has also dwindled to a ragtag team of former advisers who are still on his payroll, reminiscent of the bare-bones cast of characters that helped lift a political neophyte to his unlikely victory in 2016. Most of them go days or weeks without interacting with Mr. Trump in person.

But when he spoke on Saturday night to the North Carolina Republican convention in what was billed as the resumption of his rallies and speeches, Mr. Trump was both a diminished figure and an oversized presence in American life, with a remarkable — and many say dangerous — hold on his party.

Even without his favored megaphones and the trappings of office, Mr. Trump looms over the political landscape, animated by the lie that he won the 2020 election and his own fury over his defeat. And unlike others with a grievance, he has been able to impose his anger and preferred version of reality on a substantial slice of the American electorate — with the potential to influence the nation’s politics and weaken faith in its elections for years to come.

Still blocked from Twitter and Facebook, he has struggled to find a way to influence news coverage since leaving office and promote the fabrication that the 2020 election was stolen from him.

Some party leaders, like the Senate minority leader, Mitch McConnell, are pretending he doesn’t exist anymore, while being deferential when Mr. Trump cannot be ignored.

Others, like Senator Rick Scott of Florida, have tried to curry favor by presenting Mr. Trump with made-up awards to flatter his ego and keep him engaged in helping Senate Republicans recapture a majority in 2022.

Michael Beschloss, the presidential historian, said Mr. Trump had defied the model of ex-presidents who lose an election and tend to fade away, and the experience of Richard M. Nixon, who was treated like a pariah in the way Mr. Trump has managed to avoid.

As for being simultaneously big and small, Mr. Beschloss said: “He’s big if the metric is that politicians are afraid of him, which is one metric of power in Washington. Many Republican leaders are terrified of him and abasing themselves in front of him.”

Jason Miller, an adviser to the former president, agreed on Mr. Trump’s control over the party.

“There are two types of Republicans inside the Beltway,” Mr. Miller said. “Those who realize President Trump is the leader of the Republican Party and those who are in denial.”

Even in defeat, Mr. Trump remains the front-runner for the Republican Party’s presidential nomination in 2024 in every public poll so far. Lawmakers who have challenged his dominance of the party, like Representative Liz Cheney, the Wyoming Republican who implored her colleagues to reject him after the Jan. 6 riot by his supporters at the Capitol, have been booted from Republican leadership.

From his strange dual perch of irrelevance and dominance, Mr. Trump has been narrowly focused on three things — his repeated, false claims that the 2020 election was “rigged” and his support for efforts to try to overturn the results; the state and local investigations into the practices of the Trump Organization; and the state of his business.

Mr. Trump, who White House officials said watched with pleasure as his supporters stormed the Capitol and disrupted the Jan. 6 certification of the Electoral College vote, has told several people he believes he could be “reinstated” to the White House this August, according to three people familiar with his remarks. He has been echoing a theory promulgated by supporters like Mike Lindell, the chief executive of MyPillow, and Sidney Powell, the lawyer being sued for defamation by election machine companies for spreading conspiracy theories about the safety of their ballots.

President Biden’s victory, with more than 80 million votes, was certified by Congress once the Jan. 6 riot was contained. There is no legal mechanism for reinstating a president, and the efforts by Republicans in the Arizona Senate to recount the votes in the state’s largest county have been derided as fake and inept by local Republican officials, who say the result is a partisan circus that is eroding confidence in elections.

Nonetheless, Mr. Trump has zeroed in on the Arizona effort and a lawsuit in Georgia to insist that not only will he be restored to office, but that Republicans will also retake the majority in the Senate through those same efforts, according to the people familiar with what he has been saying.

Mr. Trump’s supporters demonstrated outside the Dallas County elections office in Dallas in November.
Tamir Kalifa for The New York Times

He has pressed conservative commentators and writers to echo his claims that the election was rigged. His focus has intensified in recent weeks, coinciding with the empaneling of a special grand jury by Cyrus Vance Jr., the Manhattan district attorney, into his businesses.

Frustrated by the lack of coverage, he has expressed his anger in news releases that still refer to him as the “45th President of the United States.”

“Next time I’m in the White House there will be no more dinners, at his request, with Mark Zuckerberg and his wife,” he said in a statement on Friday after Facebook announced it would keep its ban against him in place for at least two years. “It will be all business!”

Last week, he shut down his blog after hearing from friends that the site was getting little traffic and making him look small and irrelevant, according to a person familiar with his thinking.

Some of his aides are not eager to engage with him on his conspiracy theories and would like to see him press a forward-looking agenda that could help Republicans in 2022. People in his circle joke that the most senior adviser to the former leader of the free world is Christina Bobb, a correspondent with the far-right, eternally pro-Trump One America News Network, whom he consults regularly for information about the Arizona election audit.

In his 90-minute speech on Saturday, Mr. Trump repeatedly took aim at China for the coronavirus, ran through a litany of conservative culture war issues and ended with an extended frontal attack on voting and American democracy in which he endorsed a long list of Republican voter suppression proposals.

He raised fanciful, fact-free allegations of widespread fraud and “thousands” of dead people having voted for President Biden, called for voting to be limited in nearly all cases to voting in person on Election Day, and dismissed the results of the 2020 election as a product of the “crime of the century.”

“I’m not the one trying to undermine American democracy,” Mr. Trump told a cheering crowd after falsely accusing Democrats of stealing the 2020 election and railing against mail-in and absentee voting. “I’m the one who’s trying to save it. Please remember that.”

The former president was accompanied by his daughter-in-law, Lara Trump, who had been eyeing an open Senate seat in her home state of North Carolina but took herself out of the running on Saturday night.

“I’m saying no for now, not no forever,” Ms. Trump told the crowd. Mr. Trump said he had been waiting for her to make a decision, and he then endorsed Representative Ted Budd, who objected to the Jan. 6 Electoral College count, from the stage.

Mr. Trump’s first post-presidential rally is scheduled for later in June, followed by more appearances both for himself, paid for by his super PAC, and on behalf of House Republicans who support his agenda, advisers said.

He has been so eager for an audience that he is even billed as a speaker who will appear live, via Jumbotron, at a rally in New Richmond, Wis., where the other headliners are Diamond and Silk, the MAGA movement social media stars, and Dinesh D’Souza, who received a presidential pardon from Mr. Trump for a felony conviction of making illegal campaign contributions.

Despite the modest nature of some of the events he is interested in attaching his name to, even some of his biggest detractors are loath to write him off.

“I wish I was more confident it was ridiculous,” said Bill Kristol, a prominent “Never Trump” conservative. “It’s missing the forest through the trees to fail to see how strong he is.”

Courtney Pedroza for The New York Times

Both of his 2020 campaign managers, Bill Stepien and Brad Parscale, are on Mr. Trump’s payroll and still involved in his world. But Mr. Trump is episodically enraged with most members of his team.

This time around, Jared Kushner, his son-in-law who oversaw his 2020 campaign operation, has mostly dropped out, telling the small circle of advisers around the ex-president that he wants to focus on writing his book and establishing a simpler relationship with Mr. Trump, where he is just a son-in-law. Donald Trump Jr. has stepped in as the most politically involved family member in his father’s life.

Susie Wiles, the veteran Florida political consultant whom the former president and everyone in his orbit credit with winning the critical state in 2016 and again in 2020, oversees Mr. Trump’s fund-raising operation from Florida, shepherding the weekly conference call of the skeletal team that still runs the post-presidential operation.

In the evenings, Mr. Trump has attended fund-raisers at his Bedminster, N.J., golf course, both for his own political action committee and for Republican candidates.

But he has been eager to get back to holding rallies, announcing states where he planned to travel to before his team had finalized any venues or dates.

“If you’re a one-term president, you usually go quietly into the night,” said Douglas Brinkley, a presidential historian. “He sees himself as leading the revolution, and he’s doing it from the back of a golf cart.”

Annie Karni reported from Greenville, N.C., and Maggie Haberman from New York.