Washington CNN  — 

Sen. Rob Portman, a Republican from Ohio, on Monday criticized President Donald Trump for requesting that Ukraine and China investigate former Vice President Joe Biden, a notable break from the majority of congressional Republicans, who have defended the President or remained silent.

“The President should not have raised the Biden issue on that call, period. It’s not appropriate for a president to engage a foreign government in an investigation of a political opponent,” Portman told reporters Monday, according to The Columbus Dispatch.

“I don’t view it as an impeachable offense. I think the House, frankly, rushed to impeachment assuming certain things,” he said.

Portman’s comments join a wave of significant scrutiny from Democratic lawmakers – and a limited number of Republicans – over Trump’s requests for foreign governments to investigate Biden or his son, Hunter.

There is no evidence of wrongdoing by Joe or Hunter Biden in Ukraine. There’s also no evidence that the former vice president received any money from China, and a lawyer for Hunter Biden has pushed back on Trump’s characterization, calling it “a gross misrepresentation.”

House Speaker Nancy Pelosi declared Trump had betrayed his oath of office last month and announced that she was opening a formal impeachment inquiry into the President.

The growing controversy stems from a whistleblower complaint that alleges Trump abused his official powers “to solicit interference” from Ukraine in the 2020 election and that the White House took steps to cover it up. Trump has denied any wrongdoing.

A rough transcript released by the White House shows Trump repeatedly pushed Ukrainian President Volodymyr Zelensky in a July phone call to investigate Joe and Hunter Biden.

CNN reported Sunday that the lawyer for the first whistleblower is now representing a second whistleblower regarding the President’s actions.

Portman also said Monday that the impeachment inquiry and the significant attention it’s attracting mean “it’s going to be even harder” to move bipartisan legislation through Congress.

“It’s sad to me as hard as it is to get things done in Washington, now it’s going to be even harder. And as divided as our country already is, we are going to be even more polarized,” he said.

“I know there are strong feelings on both sides, but we need to be very careful, I think, to step into impeachment.”

CNN’s KFile reported last week that Portman was one of several Republican senators who, in 2016, had signed a bipartisan letter pushing for reforms to Ukraine’s prosecutor general’s office and judiciary, echoing calls then-Vice President Biden made at the time.