Jeff Flake’s making it clear he won’t be voting for President Trump in November’s general election.

The former senator from Arizona and vocal Trump critic who flirted with a 2020 primary challenge against the GOP incumbent tweeted on Tuesday that “Trumpism cannot be the future of the Republican Party.”

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The former senator’s tweet linked to an interview he did with the Washington Post where he definitively said: “I will not vote for Donald Trump.”

Asked if he feels comfortable voting for a Democrat, Flake answered “Yeah. This won’t be the first time I’ve voted for a Democrat — though not for president [before]. Last time I voted for a third-party candidate.”

Flake’s previously said that he didn’t vote for either Trump or Democratic presidential nominee Hillary Clinton the 2016 presidential election.

The former senator said a year ago that he could consider voting for a Democrat in the 2020 presidential election, depending on which candidate won the nomination.

The conservative lawmaker served a dozen years in the House before winning election to the Senate in 2012. He decided against running for re-election in 2018. Flake mulled his own run 2020 White House run before announcing in January of last year that he wouldn’t launch a long-shot primary challenge against the president.