Donald Trump was booed repeatedly while addressing the Libertarian Party National Convention on Saturday night, with many in the crowd shouting insults and decrying him for things like his COVID-19 policies, running up towering federal deficits and lying about his political record.

When he took the stage, many jeered while some supporters clad in “Make America Great” hats and T-shirts cheered and chanted “USA! USA!” It was a rare moment of Trump coming face-to-face with open detractors, which is highly unusual for someone accustomed to staging rallies in front of ever-adoring crowds.

Libertarians, who prioritize small government and individual freedoms, are often skeptical of the former president, and his invitation to address the convention has divided the party. Trump tried to make light of that by referring to the four criminal indictments against him and joking, “If I wasn’t a Libertarian before, I sure as hell am a Libertarian now.”

Trump tried to praise “fierce champions of freedom in this room” and called President Joe Biden a “tyrant” and the “worst president in the history of the United States,” prompting some in the audience to scream back: “That’s you.”

Libertarian candidate Gary Johnson won about 3% of the national vote in 2016, but nominee Jo Jorgensen got only a bit more than 1% during 2020’s close contest.

Libertarians will pick their White House nominee during their convention, which wraps on Sunday. Trump’s appearance also gave him a chance to court voters who might otherwise support independent presidential candidate Robert F. Kennedy, Jr. who gave his own Libertarian convention speech on Friday.

Polls have shown for months that most voters do not want a 2020 rematch between Trump and President Joe Biden. That dynamic could potentially boost support for an alternative like the Libertarian nominee or Kennedy, whose candidacy has allies of Biden and Trump concerned that he could be a spoiler.