Bill Kristol, the former editor-in-chief of The Weekly Standard, is considering challenging President Donald Trump in the 2020 Republican primary.

Kristol, who is consistently one of the most vocal anti-Trump Republicans, has been considering a run for months, a source familiar with Kristol’s thinking told The Daily Caller News Foundation.

Kristol, who remains an editor-at-large for the Standard, said he has no plans to run but declined to rule it out when asked by TheDCNF.

“No plans to run. But I’m randomly in Boston today, and happen to have had lunch with someone who does a lot of work in New Hampshire,” Kristol wrote in an email. “As he’d say, ‘Ya nevah know.'”

The New Hampshire primary, the second electoral contest after the Iowa Caucuses, is a key hurdle in the presidential nominating process.

Kristol previously sparked 2020 rumors in March when he popped up in New Hampshire to speak at “a must-show event for potential presidential contenders,” as Inside Sources noted at the time.

Kristol has consistently said that Trump needs to face a 2020 primary challenger. “We need to take one shot at liberating the Republican Party from Trump, and conservatism from Trumpism,” Kristol told the New York Times in August 2017.

Whether Kristol will be that challenger remains to be seen. Republican Nebraska Sen. Ben Sasse is often floated as a potential Trump challenger, and former GOP Massachusetts Gov. Mitt Romney — who is now running for Senate in Utah — has declined to say whether he will support Trump in 2020.

If Kristol were to run, he would be the second conservative writer to announce a primary challenge to Trump.

Conservative author Brad Thor pledged in April to run in 2020. Thor, a best-selling author, pledged to run if no other conservative would challenge Trump. “In fact, let’s make it official,” he added on Twitter shortly afterwards. “I’m in.”

Any Republican challenger to Trump would face a steep uphill climb, as Trump currently enjoys the support of 88 percent of Republicans, according to the latest Wall Street Journal/NBC News polling.

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Content created by The Daily Caller News Foundation is available without charge to any eligible news publisher that can provide a large audience. For licensing opportunities of our original content, please contact licensing@dailycallernewsfoundation.org.