George Will isn’t the first conservative to exit the Republican Party over Donald Trump this year. (Kena Betancur/AFP/Getty Images)

Conservative columnist George Will has left the Republican Party over its presumptive nomination of Donald Trump.

Will, who writes a column for The Washington Post, spoke about his decision Friday at an event for the Federalist Society in Washington.

“This is not my party,” he told the audience, the news site PJ Media first reported.

Speaking with The Post, Will said that he changed his voter registration from “Republican” to “unaffiliated” several weeks ago, the day after House Speaker Paul D. Ryan (R-Wis.) endorsed Trump.

Will did not say which presidential candidate he will be supporting instead.

Now that Donald Trump looks to be the Republican nominee for president, some of the men who attacked him most fiercely at the start of his campaign are throwing their support behind him — or at least vowing to stop insulting him. (Sarah Parnass/The Washington Post)

“I just know who I won’t be voting for,” he said.

Will has been an outspoken critic of Trump for months and a major proponent of the “Never Trump” movement. In April, he wrote a column with the headline, “If Trump is nominated, the GOP must keep him out of the White House.” In response, Trump called Will “a major loser.”

Will is one of several influential Republicans who have left the party since Trump clinched the nomination. Republican strategist Mary Matalin changed her affiliation to Libertarian the day after the Indiana primary, though she said the decision was not connected to Trump’s primary-season victory.

In an interview with Bloomberg Politics at the time, Matalin said she was still “never Hillary.” Speaking with PJ Media Friday, Will said a “President Trump” who was unopposed by Congress would be worse for the country than a Clinton presidency paired with a Republican-led Congress.

He added that it was too late for the GOP to nominate someone other than Trump. Instead, he said, Republican voters should just “make sure he loses,” then “grit their teeth for four years and win the White House.”