Trump Will Address the Libertarian Convention. Some Members Are Outraged.

Donald J. Trump likes to dwell on his successes as president, often eliding his role in events and policies that alienated some of his base. And many Republicans who were once furious about, for instance, his role in Covid-19 lockdowns and the growth of the national debt have adopted a kind of Trump amnesia in hopes of ousting President Biden from the White House.

But many Libertarians have not forgotten. And when Mr. Trump speaks at their party’s convention in Washington on Saturday night, they plan to remind him.

The Libertarian Party’s convention is, as perhaps befits a group devoted to individualism, often a raucous affair, marked by internecine disputes as members stake out their positions.

But the party’s decision to invite Mr. Trump to give a campaign speech at an event where Libertarians will select their own presidential nominee has prompted acute outrage among some members. They say it undermines the party’s integrity and gives a platform to a candidate who is, in many ways, utterly at odds with their beliefs.

As a result, Mr. Trump, whose campaign events this year have largely been on friendly territory, may face a crowd of hostile Libertarian voters on Saturday. Many say they plan to jeer him or otherwise protest his presence.

“We expected there to be a good amount of the party that is not content with Donald Trump,” said Brian McWilliams, a Libertarian Party spokesman. Some of Mr. Trump’s policies are fundamentally in conflict with the party platform, he acknowledged, and “the body is going to voice its displeasure with those policies.”

“We hope it will be polite,” Mr. McWilliams said, “but I doubt it will be quiet.”

One potential relief for Mr. Trump: Members of the public could get tickets to his event, Mr. McWilliams said. Already on Saturday afternoon, red MAGA hats were making their way into the event space.

Central to the Libertarian Party platform is a belief in limited government and unfettered individual liberties. Libertarians tend to lean to the right on fiscal issues, opposing taxes, far-reaching regulatory agencies and government spending on defense. But they skew more liberal on social issues, such as legalizing drugs and sex work, abolishing the death penalty and limiting government intervention in health and private life.

Some Libertarians have found common cause with Mr. Trump: The former president frequently rails against government bureaucracy and regulation. But his embrace of tariffs, his vows to crack down on immigration, and the vast expansion of the national debt during his administration conflict with many of the party’s positions.

Nothing compares with the lingering outrage over his handling of the coronavirus pandemic. It was on Mr. Trump’s watch, the party faithful observe, that the most severe lockdowns and mask mandates were imposed.

Robert F. Kennedy Jr., the independent presidential candidate, took aim at Mr. Trump over his handling of the pandemic in his own speech to the party on Friday afternoon.

“President Trump presided over the greatest restrictions on individual liberties this country has ever known,” Mr. Kennedy said to applause.

Recent polls suggest that Mr. Kennedy could draw support away from both Mr. Trump and Mr. Biden in the general election. His positions extend across the ideological spectrum and include some points of agreement with Mr. Trump and with the Libertarian Party. But in his speech, Mr. Kennedy promoted his anti-establishment message and spent more time attacking Mr. Trump than Mr. Biden.

During votes on official party proceedings on Friday, one attendee shouted, “I would like to propose that we go tell Donald Trump” to get lost, using an expletive. Some in the crowd cheered in response, and a vulgar chant incorporating Mr. Trump’s name broke out.

Speaking at the convention later on Friday, Vivek Ramaswamy, the entrepreneur and former Republican presidential candidate who is now an outspoken supporter of Mr. Trump, was booed at least twice when he mentioned him.

Advisers to the Trump campaign have said that Mr. Trump’s speech on Saturday will most likely highlight the overlap between his policies and the Libertarian Party’s. They view Mr. Trump’s appearance as a chance to win over voters who may see him as having a better chance to oust Mr. Biden than a third-party candidate would.

When asked about the negative response to Mr. Trump at the convention, Jason Miller, a senior adviser to the Trump campaign, said in a statement that Mr. Trump’s “America First agenda is the one that shares many of the Libertarian voters’ concerns, and he is the only candidate who can defeat Joe Biden and put an end to Biden’s assault on our Constitution, our freedoms and our God-given rights.”

Both Democrats and Republicans have argued at times that third-party candidates hurt their chances in the last two presidential elections. The Libertarian candidate in 2020, Jo Jorgensen, won 1.2 percent of the national vote. In Arizona, she won more than 50,000 votes. Mr. Trump lost that state to Mr. Biden by just over 10,000 votes.

Some Libertarian leaders and delegates resented the notion that Mr. Trump might court their vote. They called this weekend’s invitation a play for attention from the news media that undermined the integrity of the event and the party.

Richard Longstreth, a delegate from Tennessee, said, “We appear as a prize to be won, rather than as something that can stand on its own.”

And then there was the mystery of the sticker.

The campaign for one of the party’s presidential candidates, Lars Mapstead, says it spent $20,000 on ads to place around the lobby of the Washington Hilton, where the convention is taking place, including a large floor decal that read: “Let’s Deny Trump & Biden Victory on Election Night.”

Mr. Mapstead has been a vocal critic of Mr. Trump, particularly his role in increasing the national debt. In an interview with The New York Times on Friday, he said: “We reject everything about him.”

Daniel Johnson, an aide to Mr. Mapstead, said that on Thursday a man approached him, identified himself as a representative of the Libertarian Party and demanded that the advertisements be removed.

Mr. Johnson said he physically prevented the man from removing the ads after learning that he worked for an event coordinator for Mr. Trump. A video on Friday appeared to show hotel security pulling the decal off the floor.

The Trump campaign denied any involvement in the episode. A person at the Washington Hilton identified as a manager said she was not aware of ads being removed.

Mr. Mapstead blamed the Trump campaign. “It leads to that whole rigged system,” he said. “A more powerful candidate can suppress a less powerful candidate.”

Mr. Trump has made a point this year of appearing at a few events that would not traditionally be on the schedule of a Republican presidential nominee, such as a rally this week in the deep-blue Bronx.

Mr. Trump also traveled to a footwear convention in Philadelphia, where attendees trended younger and more diverse than is typical of his rallies. The crowd seemed split between those booing and those chanting in support.

“This is a slightly different audience than I’m used to, but I love this audience,” he said at the time.