Republican business executive and former gubernatorial candidate Meg Whitman announced Tuesday, in unusually blunt terms, she is crossing party lines and throwing her support behind Hillary Clinton for president. Whitman said she will not leave the Republican Party but, in an interview the New York Times, called Donald Trump a “dishonest demagogue” and unfit to be president.

Here’s more from the Times:

“I will vote for Hillary, I will talk to my Republican friends about helping her, and I will donate to her campaign and try to raise money for her,” Ms. Whitman said in a telephone interview. She revealed that Mrs. Clinton, the Democratic nominee, had reached out to her in a phone call about a month ago, one of the first indications that Mrs. Clinton is aggressively courting Republican leaders. While acknowledging she diverged from Mrs. Clinton on many policy issues, Ms. Whitman said it was time for Republicans “to put country first before party…” She said she was willing to campaign for Mrs. Clinton, said she would do her best to gather checks for her campaign and indicated she would personally give to both Mrs. Clinton and her affiliated “super PACs.” An aide to Ms. Whitman said she would personally give at least an amount in the “mid-six figures” to the Clinton effort.

Whitman, who ran for governor of California in 2010, is currently an executive at Hewlett Packard after a decade spent running eBay. Whitman was a major fundraiser for Mitt Romney in 2012 and served as the head of Gov. Chris Christie’s finance committee before he dropped out. The billionaire businesswoman had already signaled her distaste for Trump’s candidacy, calling Christie’s endorsement of, and general sucking up to, his former rival an “astonishing display of political opportunism.”

Whitman’s endorsement isn’t the first among the billionaire class—Warren Buffett and Michael Bloomberg were recent endorsers—nor is she the first Republican to diverge from the party line when it comes to supporting Trump—Republican Rep. Richard Hanna endorsed Clinton—nevertheless, Whitman’s defection is a considerable blow, in part, because she has something to lose. For a decade, the 59-year-old has been seen as a potential Republican presidential candidate and while some of that ambition has cooled a bit, and despite staying out of electoral politics since her 2010 loss to Jerry Brown, Whitman still runs in well-moneyed, influential Republican circles, making her willingness to decamp potentially far more impactful.

Read more Slate coverage of the 2016 campaign.