WASHINGTON (AP) — Donald Trump plans to use use an address tonight at the Libertarians’ national convention to court a segment of mostly conservative voters that has often been skeptical of the former president, while trying to ensure that party activists aren’t drawn to the campaign of independent Robert F. Kennedy Jr.

Libertarians will pick their White House nominee during the gathering in Washington that wraps up Sunday. Kennedy, who initially ran in the Democratic primary, addressed the convention Friday but has indicated he is not interested in being the Libertarian nominee.

Polls have shown for months that most voters, even a majority of Democrats, do not want a 2020 rematch between Trump and Democratic 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.

Libertarian candidate Gary Johnson won about 3% of the national vote in 2016, when Trump beat Democrat Hillary Clinton in a tight race. Party nominee Jo Jorgensen got only a bit more than 1% during 2020’s close contest.

Peter Goettler, president and chief executive of the libertarian Cato Institute, suggested in a Washington Post column published this week that Trump’s convention invitation violated the gathering’s core values and that “the political party pretending to be libertarian has transitioned to a different identity.”

Trump’s campaign says his appearance is part of an ongoing effort to reach would-be supporters in places that are not heavily Republican. For example, he held a rally Thursday in the Bronx during a pause his New York hush money trial. His team was expecting some at the convention to oppose Trump, but hopes he will get credit for showing up and fighting for votes.

The Libertarian ticket will try to draw support from disaffected Republicans as well as people on the left who oppose perceived government overreach. Such voters could also gravitate toward Kennedy.

The son of former Attorney General Robert F. Kennedy cites his track record of fighting for the middle class against powerful interests. He is also trying to win over conservatives who want to see the national GOP move away from Trump.

Kennedy’s anti-vaccine activism has appealed to some on the right who oppose COVID-19 vaccine mandates. He has also suggested that some of the pro-Trump rioters who stormed the Capitol on Jan. 6, 2021, may have been prosecuted for political reasons.

Trump previously praised Kennedy and once considered him for a commission on vaccination safety, but has changed his tone now. He suggested on social media that a vote for Kennedy would be a “wasted protest vote” and that he would “even take Biden over Junior.”

Trump, while in office, referred to the COVID-19 vaccine as “one of the greatest miracles in the history of modern-day medicine.” But the former president now says that, if elected, he would “not give one penny” to public schools and universities that mandate COVID-19 vaccination. He also accused Kennedy of being a “fake” opponent of vaccines — efforts that could shore up Trump’s support among some in his base who might otherwise consider defecting to Kennedy.

In his speech at the convention, Kennedy accused Trump and Biden of trampling on personal liberties in response to the pandemic that spanned their presidencies. Trump bowed to pressure from public health officials and shut down businesses, Kennedy said, while Biden was wrong to mandate vaccines for millions of workers.

Vaccines, including the COVID-19 vaccine, have been proved to be safe and effective in laboratory testing and in real-world use in hundreds of millions of people over decades. The World Health Organization credits childhood vaccines with preventing as many as 5 million deaths a year.

While no medical intervention is risk-free, doctors and researchers have proven that risks from diseases are generally far greater than the risks from vaccines.

An anti-vaccine group Kennedy led has a lawsuit pending against a number of news organizations, among them The Associated Press, accusing them of violating antitrust laws by taking action to identify misinformation, including about COVID-19 and COVID-19 vaccines. Kennedy took leave from the group when he announced his run for president but is listed as one of its attorneys in the lawsuit.

Biden, meanwhile, has trumpeted winning the endorsement of many high-profile members of the Kennedy family, in an attempt to marginalize Kennedy.

The advocacy group MoveOn Political Action, which supports Biden, has circulated a mobile billboard around the convention this weekend decrying Kennedy as “extremist,” criticizing the different positions he has taken on abortion and arguing that a vote for Kennedy will ultimately help elect Trump.