"I did it knowing full well it could very well be terminal to my career," the Republican lawmaker said this week
Rep. Adam Kinzinger
Illinois Rep. Adam Kinzinger
| Credit: Jacquelyn Martin/AP/Shutterstock

The few Republicans who broke ranks with former President Donald Trump and voted to impeach him after the U.S. Capitol riot have faced fierce backlash from the conservative base. But one of those GOP lawmakers says the issue was more important than party politics.

"I did it knowing full well it could very well be terminal to my career," Illinois Rep. Adam Kinzinger, 42, told CNN's David Axelrod this week. That interview came after a write-up in The Washington Post detailing Kinzinger's years-long break from the pro-Trump portion of a fractured Republican Party.

Earlier this month, Kinzinger and nine other GOP members of the House of Representatives voted to impeach Trump, 74, for inciting the Jan. 6 riot, which left five people dead.

It was the second time Trump was charged by the House — the first-ever president twice impeached — and it garnered the most-ever votes from representatives in a president's own party.

Kinzinger, a former Air National Guard pilot who served two tours in Iraq, has been one of the few Republicans to consistently criticize Trump, his party's standard-bearer, as well as to speak out against extremist conspiracy theories taking root among their supporters.

Last year, the Illinois lawmaker talked with PEOPLE about his push against conspiracy theorists amid the 2020 election, which featured a handful of congressional candidates who had voiced support for QAnon, a bizarre and macabre network of beliefs including that Trump is at war with secret evildoers.

Two of those congressional candidates ended up winning their election and are now in office.

"There's a lot of people [in Congress] who don't see this as the problem I see it as, which is not the near term," Kinzinger told PEOPLE in November, about two months before the attack on the Capitol, which was fueled by baseless claims that President Joe Biden (and, depending on whom you asked, a cabal of international accomplices) had stolen the election from Trump.

Rep. Adam Kinzinger
Rep. Adam Kinzinger
| Credit: Susan Walsh/AP/Shutterstock

Well-versed in observing conspiratorial chatter online, Kinzinger told the Post this week that he brought a gun to Congress on Jan. 6 out of fear the pro-Trump rally down the street from where Congress was meeting to certify Biden's win could turn violent.

Kinzinger advised his staff — and his wife, a former communications staffer for then-Vice President Mike Pence — to stay home that day.

Hours later, he said, he feared the worst when security alarms rang out inside the Capitol.

"I got the chills, frankly," Kinzinger told CNN. "I stood up and felt a real dark kind of feeling. A sense of evil kind of descending over the place."

The lawmaker said he barricaded himself in his office, ready to fight for his life: "I had the gun out, and was like, 'You know, it may come down to I have to defend myself,' " Kinzinger said. "We had no idea at all what was going on."

Rep. Adam Kinzinger
Rep. Adam Kinzinger
| Credit: KEVIN DIETSCH/POOL/AFP via Getty

Since the attack and the vote to impeach Trump for inciting it, the GOP lawmaker, first elected in 2010, told the Post he has received threatening messages for breaking with the former president.

"The ones I worry about are not the ones that type out a threat," Kinzinger said. "It's the ones who just do it."

Like other Republicans who voted to impeach, he also faced backlash back home in Illinois' 16th Congressional District. The Post reports at least one 2022 challenger has filed paperwork in hopes of unseating him. The candidate named their campaign committee: "Impeach Adam Kinzinger 2022"

Kinzinger previously told PEOPLE he was "not confident" other GOP lawmakers would join him in speaking out against radical conspiracies, but he remained "hopeful" some Republican colleagues will stand up and join him.

"It's incumbent upon you to keep your house in order," he said.

"Getting re-elected is important, but it's about leadership," he said. "Whatever side has the conspiracy theory — and there are some on the left of course — it's got to be members of their own party calling them out."