Early in his speech at the Libertarian Party’s national convention on Saturday, Donald J. Trump told the party’s delegates bluntly that they should nominate him as its candidate for president. He was vigorously booed.
When the jeers died down, Mr. Trump, visibly frustrated with the rowdy reception he had received ever since taking the stage, dug in and went a step further, seeming to insult the very group that had invited him.
“Only do that if you want to win,” he said of nominating him. “If you want to lose, don’t do that. Keep getting your three percent every four years.”
The boos began anew, only louder.
Mr. Trump’s speech was without modern precedent: the presumptive nominee of a major political party giving a prime-time address at another party’s convention.
But as Mr. Trump tried to urge Libertarians to unite behind him in a shared effort to defeat President Biden, he was greeted with a hostility absent from the friendly crowds at his rallies, which overshadowed his appeals to their common cause.
Mr. Trump’s speech was delivered to an audience that included supporters wearing red MAGA hats, as well as Libertarians who were resentful of his presence at the convention where they will select their own presidential nominee.
Throughout his remarks, the room’s warring factions tried to drown each other out, a dynamic that immediately emerged when Mr. Trump was called to the stage.
Practically every time Mr. Trump was booed, his supporters responded by chanting, “We want Trump.” If those in MAGA hats cheered on a policy pronouncement, many of those opposed to Mr. Trump’s presence booed or shouted insults.
Often, the cycle ended only when someone began chanting, “End the Fed,” a unifying policy plank that everybody in attendance seemed to agree on.
Mr. Trump appeared irked by the chaotic atmosphere. He seemed to rush through his speech, appearing to stick to prepared remarks and avoiding the digressions or banter that often characterize his rallies.
Still, the reception was not entirely negative, with Mr. Trump able to find shared ground with the Libertarian Party on a number of issues.
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.
As he often does, Mr. Trump railed against government bureaucracy and regulation, remarks that were largely well-received. He promised that, if elected, he would put Libertarians in his cabinet and in senior positions, a vow that elicited some of the night’s loudest cheers.
Mr. Trump also promised to commute the life sentence of Ross Ulbricht, the founder of the black-market website Silk Road who was sentenced to life in prison in 2015. His release from custody has been a major demand of Libertarians, and many of those in attendance waved “Free Ross” signs.
But by and large, any moments of concord were eclipsed by raucous dissent. After speaking for 35 minutes, Mr. Trump offered a closing note: “You can either nominate us and put us in the position, or give us your votes.” Another chorus of boos provided the night’s final moment.
Well ahead of his speech, the Libertarian Party’s decision to invite Mr. Trump to its convention prompted acute outrage among some members, who said it undermined the party’s integrity and gave a platform to a candidate who is, in many ways, utterly at odds with their beliefs.
D’Anne Welch, a delegate from Texas, said she was stunned that Mr. Trump, a Republican, was given time to speak that effectively delayed the party’s decision on its nominee, adding that she was deeply opposed to his efforts to secure the party’s support.
“He’s going to make himself sound Libertarian,” Ms. Welch said. “But he’s the ultimate authoritarian.”
Mr. Trump’s efforts to engage with the Libertarian Party date back months. Richard Grenell, a former ambassador to Germany and former acting director of national intelligence, has been key in trying to build Mr. Trump’s support among some Libertarian activists and donors.
After the speech, Mr. Grenell suggested in a post on social media that he had arranged Mr. Trump’s attendance at the convention, and he blasted liberal critics of his appearance. “Donald Trump doesn’t fear dissenting views,” he wrote. “Only your team does.”
The disagreements over Mr. Trump’s invitation were evident throughout the convention. 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.
On Saturday, hours before his speech, a number of Libertarian delegates — who had paid to attend the convention — arrived in the ballroom to find that a number of Trump supporters had taken reserved seats in the front of the room. The party’s chair, Angela McArdle, urged a change in seating arrangement.
“I don’t want to fight with people or beg and plead,” Ms. McArdle told the Trump supporters. “Let’s just make room for the delegates, because those are the people you’re trying to persuade right now. Because you’re already sold. Our delegates are not sold, and President Trump is here to try to sell them.”
Trump campaign advisers and supporters have argued that Mr. Trump’s appearance offered 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.
After the speech, Senator Mike Lee of Utah, a Republican with libertarian leanings who was in attendance, said Mr. Trump’s speech was a success regardless of whether he received the party’s nomination. “The speech was a home run,” he said, “because there are Libertarians all over the country watching this.”
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.
Mr. Trump was not the only non-Libertarian to address the convention. Robert F. Kennedy Jr., the independent presidential candidate, took aim at Mr. Trump over his handling of the coronavirus pandemic in his own speech to the party on Friday afternoon.
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.
Some Libertarian leaders and delegates resented the notion that Mr. Trump or Mr. Kennedy might court their vote, calling this weekend’s invitations a play for attention from the news media.
And then there was an incident that exemplified the tension surrounding Mr. Trump’s presence: 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.”
