Former Republican senator Jeff Flake has decided he's not going to challenge Trump for the Republican presidential nomination in 2020

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As a senator, Jeff Flake toyed with refusing to vote for President Trump's Supreme Court nominee Brett Kavanaugh but ultimately voted to confirm him anyway.

• Jeff Flake, who criticized President Donald Trump from his perch as a Republican senator in Arizona, has decided not to run for president.
• He announced on "CBS This Morning" that he will be a CBS contributor instead.
• Flake built a record of often criticizing Trump but then voting for his policies anyway.

Former Republican senator Jeff Flake has decided not to run for president in 2020, he announced on "CBS This Morning" Tuesday. Instead, he is taking a role as a CBS contributor.

"I've always said that I do hope there is a Republican who challenges President Trump," he said. "That will not be me."

Flake represented Arizona in the Senate for two terms before announcing in 2017 that he would not run for re-election. He has often criticized President Donald Trump - and even denounced him in his closing Senate address - only to remain in the Republican party and frequently throw his support to Trump's policies. Flake voted in line with Trump's positions 81.3% of the time, according to FiveThirtyEight's tracker, more than most other Republican senators in the 115th congress.

His record drew Trump's mockery. When Mitt Romney, elected from Utah as a Republican senator in 2018, wrote a Washington Post op-ed criticizing Trump, Trump shrugged it off and tweeted "Question will be, is he a Flake?"

Read more: Mitt Romney's scathing Trump op-ed draws comparisons to Jeff Flake and enrages president's GOP allies

At CBS, Flake will work on a series of pieces about legislation that seeks compromise between the Democratic and Republican parties, such as his sponsorship of criminal justice reform at the end of his final term.

"There can be many more examples of that, and that's what this series will look at," Flake said on "CBS This Morning." "Those areas of common ground around the country."

• Read more:
• Mitt Romney's scathing Trump op-ed draws comparisons to Jeff Flake and enrages president's GOP allies
• 'Somebody does need to challenge the president': Republican Jeff Flake calls for civility, says Trump 'owns' the government shutdown
• Flake says a Republican, possibly even him, should challenge Trump in 2020
• Sen. Jeff Flake bashes Kavanaugh for being too 'sharp and partisan' in Senate hearing, says 'we can't have that on the court'