HAGERSTOWN, Md. — As dusk settled over the racetrack on the edge of town, a truck driver stood on a trailer being used as a makeshift stage and held forth on the sins of the politicians in the nation’s capital, an hour and a half’s drive southeast.

“Lock them up!” a man yelled from the crowd of several hundred.

“It’s all or nothing!” called out another, waving a large American flag.

Tracy Graham, a Mary Kay consultant from Suffolk, Va., held her own flag neatly folded in her hands. She had driven five hours to the Hagerstown Speedway to show her support for the People’s Convoy, a demonstration against Covid-19 vaccine mandates modeled on the one that occupied Canada’s capital city of Ottawa for weeks.

But for Mrs. Graham, a Republican who is active in local politics, the American convoy was about far more than Covid restrictions. Mask and vaccine mandates were just one example of how “our freedoms have been coming down brick by brick over time,” she said. She’d asked the truckers to sign her flag and was thinking about framing it when she returned home. “This is a part of history,” she said.

Historical and biblical allusions are tossed around loosely at the convoy’s speedway headquarters. Organizers have compared the convoy’s weathering of a snowstorm last weekend to the Continental Army’s winter encampment at Valley Forge, Pa., and their caravans around the Washington Beltway, which they are circuiting daily, to the Israelites’ marches around Jericho.

But whether the convoy can match its own aspirations remains uncertain. The 100 or so trucks — plus an entourage of pickups, cars and camper vans — that head off toward Washington daily have neither matched the scale of the Canadians’ city-paralyzing demonstration, which drew thousands of trucks at its peak, nor summoned the same media attention.

For the moment, the protest is perhaps most notable as a window onto the evolution of the American right in the wake of Donald J. Trump’s presidency, and one that Republican politicians are watching. Although organizers insist that their demonstration is nonpartisan and narrowly focused on Covid restrictions, in practice, it is animated by a broad, familiar array of conservative and right-wing issues and grievances. Complaints about schools mix with far-right conspiracy theories and refusal to accept the 2020 election results.

This worldview is increasingly incorporating ideas from the anti-vaccine movement, some of them preceding the Covid outbreak, even as the virus has receded and Covid restrictions have eased.

This week, one side of the stage was piled with books written by Robert F. Kennedy Jr., an anti-vaccine activist; while near the other, a vendor sold stickers saying “WHEN I DIE DON’T LET ME VOTE DEMOCRAT.” On Wednesday evening, Dr. Paul Alexander, a former official in Mr. Trump’s Health and Human Services Department who has become a prominent personality in the anti-mandate movement, called for President Biden to pardon the defendants facing charges related to the Jan. 6, 2021, storming of the Capitol.

On Friday, organizers yielded the microphone briefly to a motorcyclist in leather chaps, who exhorted the mostly white crowd to strip the “Black Lives Matter” slogan from the a street near the White House where it has been painted in giant letters. “We’re going to take it back,” he declared.

Banners with symbols of the Three Percenters, an armed extremist movement, have been flown from some trucks in the convoy. Two young men in the attire of the Proud Boys, the far-right organization, were milling around the camp on a recent morning.

Asked in interviews what had drawn them to the protest, demonstrators spoke of ending a national emergency order Mr. Biden had extended in February, as well as a handful of remaining federal restrictions — vaccine requirements for military service members, for instance, and mask requirements on airplanes.

But most of the dozen demonstrators interviewed also enumerated other motivations, from concern over gun rights and abortion to the Trump-aligned QAnon conspiracy theory. Not all of them identified as Republicans, but all who disclosed how they voted in 2020 had supported Mr. Trump, and said they believed or at least suspected that the election had been rigged against him.

“We’ll be satisfied when Biden’s gone, when Harris is gone and Pelosi’s gone,” Curt Martin, a 73-year-old truck driver from upstate New York, said. “When they’re gone, we’ll be happy. We’ll go home. But not until then.”

Besides an end to the emergency order, the convoy is calling for an investigation into Covid-19’s origins and the federal response, and is encouraging state-level protests against local restrictions.

“We are still looking for accountability,” Brian Brase, a convoy organizer and its most visible spokesman, said.

These are narrower aims than the Canadian protest, befitting a country where there are relatively few Covid mandates left to protest against. In the United States, unlike Canada, federal vaccine mandates for private employers were never implemented and few state-level Covid restrictions remain.

When the convoy first arrived after a cross-country trip from California on March 4, its organizers avoided trying to shut down Washington as the Canadian demonstrators had Ottawa, opting instead for relatively orderly laps around the Beltway. When these failed to make any great impression, drivers began making forays into the city’s heart, with noisy excursions down residential streets, drawing the attention of law enforcement and, increasingly, angering residents.

Meanwhile, some Republican politicians and candidates have come to pay their respects at the speedway camp, including Senator Ted Cruz of Texas and Doug Mastriano, a Pennsylvania state senator and candidate for governor who chartered buses to Mr. Trump’s Jan. 6 rally preceding the storming of the Capitol. At least nine other Republican senators and congressmen have met with the organizers during their visits to Capitol Hill.

Some of these meetings were arranged by Axiom Strategies, a Republican consulting firm whose principals have worked for Mr. Cruz and Gov. Glenn Youngkin of Virginia and offered its services pro bono to connect the convoy with Republican politicians.

“This is one of the major political movements in America right now,” said Matt Wolking, Axiom’s vice president for communications.

Wolking and other Republican strategists argue that Covid restrictions remain a Democratic vulnerability in 2022, despite the few policies still in place. The Biden administration’s vaccine-or-testing mandate for large employers was blocked by the Supreme Court in January, and in early February, Democratic governors rushed to repeal their states’ indoor mask mandates, leaving only Hawaii with such a mandate in place. The Centers for Disease Control and Prevention has since eased mask guidelines as the spike in infections from the Omicron variant has largely abated.

“I think the voters have moved on,” said Brian Stryker, a partner at Impact Research, a Democratic polling firm. “The Republicans very much will look like they are looking backward and talking about something voters don’t really care about.”

Convoy organizers insist they will continue demonstrating until their demands are met, and the Hagerstown encampment has taken on an air of increasing permanence. There have been barbecues, campfires and, on Wednesday morning, a wedding.

Along the gravel entrance road to the racetrack, Sherrie Campbell, a retired truck driver from Dallas, Tex., stood alongside her black Chevy Silverado, the exterior of which was painted with slogans related to QAnon, a conspiracy theory about the existence of a global pedophilic cabal that includes Democratic leaders. References to QAnon have appeared on a number of convoy vehicles. One truck pulled a trailer decorated with an immense American-flag-patterned skull topped by Mr. Trump’s distinctive hair, alongside the phrase, “Q Sent Me.”

Since arriving in Hagerstown, Ms. Campbell has been sleeping in the back seat of her truck’s extended cab, on a bedroll covered with an American flag-patterned bedspread. She said she would be staying with the convoy until it had achieved the aim of “getting our freedom back.”

“People show up here because this is kind of the last stand of hope,” said Tyler Lee, 34, a real estate investor who is running for Congress as a Republican in a heavily Democratic congressional district in North Carolina. Mr. Lee had driven from Charlotte, N.C., to meet the convoy in Adelanto, Calif., in February and traveled with it ever since.

He gave Mr. Cruz credit for his visit to the convoy site. But he thought politicians should spend more time at the camp, perhaps even spend the night as he himself did.

“You can get a real pulse of what is going on in America,” he said.

As the speedway occupation seemed to stretch ahead indefinitely, however, Mr. Lee was eyeing the calendar. His primary, on May 17, was coming up soon.

“I’ve committed to these guys,” he said. Still, “I’m taking it day by day,” he said. “Because I do have a campaign to run.”