On Saturday afternoon, Trump tweeted:

I’m hearing that the Great People of Utah are considering their vote for their Pompous Senator, Mitt Romney, to be a big mistake. I agree! He is a fool who is playing right into the hands of the Do Nothing Democrats! #IMPEACHMITTROMNEY

— Donald J. Trump (@realDonaldTrump) October 5, 2019

Romney, who has been one of the few Republican voices that has been critical of Trump, had tweeted about the president Friday.

When the only American citizen President Trump singles out for China’s investigation is his political opponent in the midst of the Democratic nomination process, it strains credulity to suggest that it is anything other than politically motivated.

— Mitt Romney (@MittRomney) October 4, 2019

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

Nebraska Senator Ben Sasse, a Republican, also was critical of Trump, saying in a statement to the Omaha World-Herald: ‘‘Americans don’t look to Chinese commies for the truth. 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.’’

RELATED: Romney is becoming a leading voice in criticizing Trump. But what’s his next move?

The references to China began Thursday, when Trump defended himself against allegations that he privately pressured Ukraine to investigate Joe Biden and his son by inviting a geopolitical rival to launch a probe, the Associated Press reported.

‘‘China should start an investigation into the Bidens,’’ Trump said after being asked about trade negotiations with the country.

Trump on Friday argued he was not specifically targeting a political foe, but merely pushing countries to clean up corruption. There is no evidence that the Bidens were involved in criminal corruption in either Ukraine or China.

Trump also tweeted about the ongoing impeachment inquiry.

The so-called Whistleblower’s account of my perfect phone call is “way off,” not even close. Schiff and Pelosi never thought I would release the transcript of the call. Got them by surprise, they got caught. This is a fraud against the American people!

— Donald J. Trump (@realDonaldTrump) October 5, 2019

RELATED: Romney, Sasse break from GOP on Trump’s China remarks


Material from the Associated Press is included in this story.