WASHINGTON – Sen. Susan Collins joined two other Republican senators in criticizing President Trump for asking China to investigate Joe and Hunter Biden.

“I thought the president made a big mistake by asking China to get involved in investigating a political opponent,” Collins said Saturday, according to the Bangor Daily News. “It’s completely inappropriate.”

Collins joins Sens. Mitt Romney (R-Utah) and Ben Sasse (R-Neb.) in speaking out against the president’s actions.

House Democrats have launched an impeachment inquiry against Trump over him pressuring the Ukranian president to probe the former vice president and his son over business dealings in the country.

Trump stalled nearly $400 million military aid to Ukraine around the same time.

Trump subsequently called on China to investigate the Bidens, as Hunter Biden did business in that country, too.

Most Republicans have stayed in line with the president.

Sen. Ron Johnson (R-Wis.) had a contentious back-and-forth with NBC’s Chuck Todd after the “Meet the Press” host asked him about comments he made to the Wall Street Journal.

Johnson had said he “winced” at the suggestion that Trump was holding back military aid from Ukraine if the country didn’t probe 2016 election meddling.

“My reaction was: Oh, God. I don’t want those two things combined,” he said.

Asked about the comments Sunday, Johnson attacked the CIA, FBI and the news media.

“Can we please answer the question I asked you instead of trying to make Donald Trump feel better here that you are not criticizing him?” Todd said. “I’m just trying to ask a simple question of what made you wince.”

Johnson eventually explained that he didn’t want aid tied to an investigation.

“When I asked the president about that, he completely denied it. He adamantly denied it. He vehemently, angrily denied it. He said, ‘I’d never do that,’” Johnson said, defending Trump.

Sen. Marco Rubio (R-Fla.) suggested that Trump was kidding when he said Thursday morning that “China should start an investigation into the Bidens.”

“He’s pretty good at getting everybody fired up,” Rubio said. “I don’t think it’s a real request.”

Rep. Jim Jordan (R-Ohio), a top Trump ally in the House of Representatives, made similar comments Sunday.

“I don’t think he really meant go investigate. Do you think China’s going to investigate him? We know they’re not,” Jordan said on ABC’s “This Week.” “I just don’t think that’s what the president was really saying.”

Meanwhile on Twitter, Trump was defending his requests to Ukraine and China to investigate Hunter Biden’s business dealings in the two countries.

“There is NO WAY these can be legitimate transactions? As lawyers & others have stated, as President, I have an OBLIGATION to look into possible, or probable, CORRUPTION!” Trump wrote.