A formal impeachment inquiry has failed to dent President Trump’s re-election bid — with a new survey showing he would likely defeat the Democratic front-runners in head-to-head battles.

The poll of 1,000 registered voters taken this weekend as the House of Representatives prepared a formal impeachment vote found Trump defeating former Vice President Joe Biden by 3 percentage points and Sen. Bernie Sanders by 5 points.

Trump also held an 8-point lead over Sen. Elizabeth Warren and a 10-point lead over South Bend, Indiana, Mayor Peter Buttigieg, according to the USA Today/Suffolk University Poll published Monday.

The survey also showed high support for a third-party candidate. In a head-to-head between Trump and Biden, 11 percent of respondents said they wanted an unnamed third option.

That number rose to 15 percent when voters were asked to choose between Trump and Buttigieg and Trump and former New York City mayor Mike Bloomberg.

“We know third-party candidates have minimal chance to win a presidential election but a high probability to make a difference in a state’s outcome,” David Paleologos, director of Suffolk’s Political Research Center, told USA TODAY.

“Every ballot has third-party candidates who receive critical votes. When you give voters more than two options for president, you see how it impacts the major two parties.”

A poll released Sunday also found Trump’s job performance rating ticked up in the weeks of the impeachment hearings.

Senate Majority Leader Mitch McConnell on Tuesday knocked the request for witnesses at the impeachment trial and called the impeachment articles drafted by House Democrats a “slapdash work product” that was “dumped on us in the Senate.”