Sen. Mitt Romney is one of the few Republicans in Congress criticizing President Donald Trump for asking Ukraine and China to help dig up dirt on a Democratic rival while others in Utah’s federal delegation are mainly staying mum.

Romney, a Utah Republican and member of the Senate Foreign Relations Committee, said Friday that it “strains credulity” for Trump to argue he’s not acting politically by calling on foreign nations to investigate former Vice President Joe Biden.

Trump, already facing a House impeachment inquiry over his conversations with Ukraine’s president, added fuel to the fire this week, when he publicly suggested that China launch an investigation into Biden based on unsubstantiated — and mostly debunked — allegations of corruption.

Romney — who had already distanced himself from most Senate Republicans by calling Trump’s actions “troubling in the extreme” — questioned Trump’s motivations for singling out Biden for investigations amid the Democratic Party’s nominating process for the 2020 election.

“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,” Romney wrote on Twitter.

He continued: “By all appearances, the President’s brazen and unprecedented appeal to China and to Ukraine to investigate Joe Biden is wrong and appalling."

While Romney has called out the president’s actions, he has not directly supported an investigation, like the one House Democrats are now leading. He also did not comment Friday morning on texts from some of Trump’s envoys that shine new light on the accusations that the president was pressuring Ukraine to investigate Biden and his son Hunter. Hunter Biden had been on the board of a Ukrainian energy company that had previously been under investigation.

Romney has been the most critical of Trump in Utah’s congressional delegation.

Utah’s only Democrat in Congress, Rep. Ben McAdams, has tried to avoid the topic when he can, describing himself as a potential member of the “jury," a reference to a possible vote for articles of impeachment. After more than two weeks avoiding saying he backed the impeachment inquiry, McAdams said Friday he supported the proceedings.

Sen. Mike Lee on Friday brushed off Trump’s latest comments on China, saying they weren’t about helping the president’s reelection but China protecting itself.

“I read Trump’s statement as not asking China to investigate but suggesting that it would be in China’s interest to do so," Lee said in a statement.

Reps. Rob Bishop, John Curtis and Chris Stewart — all Utah Republicans — did not respond Friday to requests for comment.

Stewart, a member of the House Intelligence Committee, has emerged as a staunch defender of Trump as the controversy has continued to churn. On Friday, he signed on to legislation to censure Intelligence Committee Chairman Adam Schiff, D-Calif., for his remarks in a hearing last week that inaccurately described Trump’s request to the Ukrainian president.

“His actions misled the American people and have made a mockery of the impeachment process,” Stewart said.

Romney now joins GOP Sen. Ben Sasse of Nebraska in raising alarms about Trump’s comments.

“Hold up: Americans don’t look to Chinese commies for the truth,” Sasse said in a statement to the Omaha World-Herald. “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.”

Sasse, though, also jumped on Schiff for running a “partisan clown show” with the impeachment inquiry.

Sen. Marco Rubio, R-Fla., said he didn't take the president seriously when he stood before Marine One on Wednesday and said Ukraine should probe the Bidens and that he would consider asking China to do the same.

“I don’t know if that’s a real request or him just needling the press knowing that you guys are going to get outraged by it,” Rubio said. “He’s pretty good at getting everybody fired up. He’s been doing that for a while and the media responded right on task.”

If a majority of House members vote to impeach Trump, those articles then go to the Senate, where a trial would take place. It would take 67 votes, in the Republican-controlled Senate to remove Trump from office.