Republican Senator Lindsey Graham, chair of the senate judiciary committee, made the prediction on Twitter on Tuesday morning.
He declared that the ‘radical left’ is now in charge of the Democratic Party, meaning attempts by House Speaker Ms Pelosi to avoid divisive impeachment proceedings will fail.
“Nancy Pelosi is not in charge of the Democratic Party. The radical left is in charge.
“So, I will expect that there will be impeachment proceedings against President Trump.”
Speaking to Sean Hannity on Fox News on Monday night, he said he expected a “stampede” by the so-called radical left to impeach the president.
He said he “hates” that Mr Trump will have to go through the process, but believes the Mueller report, released in a heavily redacted form last week, “vindicates” the president.
The end result of impeachment proceedings, he predicted, would be Mr Trump’s re-election in 2020.
Any impeachment process would be extremely unlikely to pass the Senate.
His comments come in the wake of Ms Pelosi, a pragmatic party elder not known for grand gestures, urging colleagues to pursue other options to impeachment this week.
She said it was “important to know that the facts regarding holding the president accountable can be gained outside of impeachment hearings”.
She condemned Mr Trump’s “highly unethical and unscrupulous behaviour” as revealed in Robert Mueller’s report, but warned her party not to become overly obsessed with the specific way it responded.
“While our views range from proceeding to investigate the findings of the Mueller report or proceeding directly to impeachment, we all firmly agree that we should proceed down a path of finding the truth,” Ms Pelosi wrote to colleagues ahead of a conference call.