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President Donald Trump lashed out at Sen. Mitt Romney (R-Utah) Saturday morning, calling him a “pompous ‘ass’,” and saying that the senator is bad for Republicans.

After tweeting that “the so-called Whistleblower’s account of my perfect phone call is ‘way off’,” Trump aimed his twitter fusillade at Romney, a frequent critic of the president.

Somebody please wake up Mitt Romney and tell him that my conversation with the Ukrainian President was a congenial and very appropriate one, and my statement on China pertained to corruption, not politics. If Mitt worked this hard on Obama, he could have won. Sadly, he choked! — Donald J. Trump (@realDonaldTrump) October 5, 2019

Mitt Romney never knew how to win. He is a pompous “ass” who has been fighting me from the beginning, except when he begged me for my endorsement for his Senate run (I gave it to him), and when he begged me to be Secretary of State (I didn’t give it to him). He is so bad for R’s! — Donald J. Trump (@realDonaldTrump) October 5, 2019

One reason for the president’s recent assault on a man he once interviewed to be his Secretary of State is likely Romney’s tweet on Friday that described Trump’s “brazen and unprecedented appeal to China and to Ukraine to investigate Joe Biden” as being “wrong and appalling.”

By all appearances, the President’s brazen and unprecedented appeal to China and to Ukraine to investigate Joe Biden is wrong and appalling. — Mitt Romney (@MittRomney) October 4, 2019

The former GOP presidential nominee is among the very few Republicans to go after Trump on his use of American foreign policy to target a domestic political rival. He is joined by Sen. Ben Sasse, (R-Neb.) who on Thursday slammed the president for asking China to investigate the Biden family.

“Hold up: Americans don’t look to Chinese commies for the truth,” Sasse, who is not running for reelection, told the Omaha World-Herald on Thursday. “If the Biden kid broke laws by selling his name to Beijing, that’s a matter for American courts, not communist tyrants running torture camps.”

Trump fired off the tweets en route to the Trump National golf course in Virginia, just outside of Washington, DC. They came after Trump spent Friday night into early Saturday morning tweeting attacks on Biden and clips from Fox News.