One thing to understand about Adam Kinzinger is that he knows how this will end.

“The only hope you have is to accept the fact that you’re already dead,” the Republican congressman from Illinois says. He is quoting a scene from the World War II series “Band of Brothers” in which an officer dresses down a soldier who hid from battle. The officer continues: “And the sooner you accept that, the sooner you’ll be able to function as a soldier is supposed to function.”

Kinzinger, who is also a pilot with the Air National Guard, took those words as an order.

His embrace of this fatalistic credo made it easier for him to fly planes into enemy territory during tours in Iraq and Afghanistan. It made it easier for him to object late last year as President Donald Trump and some of his congressional colleagues amplified the myth of a “rigged” election, stoking violent revenge fantasies among the party’s politically valuable give-me-MAGA-or-give-me-death contingent. And it made it easier for Kinzinger, a young, square-jawed Republican with his whole political life ahead of him, to vote to impeach Trump in the aftermath of the failed insurrection at the U.S. Capitol.

“I’m willing to blow this whole thing out of the water at all times,” Kinzinger said of his career in politics. The 42-year-old congressman, who last fall won reelection easily, spoke to The Washington Post from his office a week after the attack on the Capitol. He was the only Republican to vote in favor of a resolution urging Vice President Mike Pence to invoke the 25th Amendment and strip Trump of his presidential powers and one of 10 Republicans to vote to impeach Trump for inciting a riot at the Capitol.

Rep. Adam Kinzinger (R-Ill.) posted a video on Jan. 7, 2021, the day after pro-Trump riots at the Capitol, saying, “It is time to invoke the 25th Amendment.” (@RepKinzinger/Twitter)

Now, as the Senate prepares for Trump’s impeachment trial, Kinzinger finds himself prepared to learn what his outspoken criticism of the former president will cost him.

“Those 10 [Republican] colleagues who voted to impeach all have to know there’s a decent chance they lose their jobs next year,” says Joe Walsh, a former Illinois congressman who challenged Trump in last year’s presidential primary.

The upside, practically speaking, has been elusive. Before the Capitol siege, Kinzinger had spoken out against baseless pro-Trump claims, and in the wake of the attack, he has condemned Republican colleagues and leaders of Christian churches for backing Trump’s false claims that the election was stolen from him. But this tack has not been politically rewarding so far. “I’ve felt very isolated in my party,” Kinzinger told The Post. “Very isolated and very lonely.”

Trump is out of office but remains in control of the Republican Party — a commander in absentia. Where does that leave Adam Kinzinger, a political soldier who broke ranks?

“If there was any political calculation, it’s to be one of the leaders of the anti-Trump wing of the Republican Party,” Walsh says. “And I give him credit for that. I just don’t think they have a prayer.”

When he was 6 years old, Kinzinger was a Democrat — or, at least, he marched a Democratic candidate's campaign sign around his Jacksonville, Fla., cul-de-sac during the city's mayoral primary. (In retrospect, Kinzinger thinks he was mostly into hot pink campaign signs, but was still bummed when his guy lost.)

After a couple of years in Florida, the Kinzinger family moved back to Illinois, where his mother taught public school and his father ran nonprofit organizations. In junior high, the other boys sprouted; Kinzinger remained small. His brother topped six feet, like their dad. Kinzinger, the youngest of three, maxed out at 5-foot-9.

“As a guy, it’s always about being tough, right? Well, now, all of a sudden, when you have people that have grown and you haven’t, you’re, like, not as tough as them,” he says. “And I think that builds a dynamic where it can lead to self-esteem issues.”

The lack of confidence continued into high school. He started drinking at age 16. He can remember drinking before school one morning, just to try to be cool. In his first semester at Illinois State, he joined a fraternity and came home with a 2.5 GPA. The next semester, he got a 0.8 and was kicked out. He spent the next six months living with his parents and working as a manager in the furniture section of a department store. He tried to date the daughter of a fellow store manager, only to learn that he forbade her to go out with him.

“Because I was a loser, or whatever,” he says now. “And I’m, like, ‘Yeah, man, I suck.’ ”

Chastened by failure, he started talking to God and eventually went back to college. At age 20, he ran for a seat on the county board. “Somebody jokingly told me I should, and I thought they were serious,” he says. He conducted his campaign almost exclusively via phone, worried that if he showed up in person, voters would see how young he looked and laugh him off the front porch. (He won the race.)

A month after Sept. 11, 2001, he signed up to join the Air National Guard.

Kinzinger saw “Band of Brothers” when it aired in 2001. Sometime later, he heard his brother give a speech to a church group, highlighting the advice the on-screen officer gave that frightened soldier: The only hope you have is to accept the fact that you’re already dead.

During two tours in Iraq, Kinzinger flew planes that transported troops who were tasked with killing or capturing known terrorists, often taking mortar attacks along the way. “There were a few heightened moments,” he says. “I didn’t have any fear. It was just my belief that, ‘We’re here for a moment like this.’ ”

In 2006, Kinzinger encountered another heightened moment. On a night out in Milwaukee, he and his girlfriend were walking along a street full of popular bars and restaurants after dinner with a friend. Suddenly, they heard a woman screaming, “He cut my throat! He cut my throat!” The woman, clutching her neck, looked to Kinzinger for help as her boyfriend held the bloody knife.

“I remember going to thoughts of, ‘If I watch her die, I can’t live with myself for the rest of my life,’ ” he says. “But the second thought was, ‘If I fight him, I’m going to die.’ ”

Kinzinger was able to wrap his arm around the man’s neck and pin him to the ground until the police arrived. The woman survived, and Kinzinger walked away unscathed. He later received commendations from the Air Force and the National Guard.

Accepting the inevitability of The End can make you a hero — but not always, and not to everyone. In politics, when you take drastic action in an emergency, some people will believe you’re the man with the knife.

When the Capitol's emergency alert system sounded on Jan. 6, Kinzinger felt a chill run through his body.

He had been worried about violence in the District for weeks. Kinzinger tracks conspiracy theory-addled online chatter and grew concerned about the rhetoric at Trump’s post-election rallies. He told his staff to work remotely the day of the certification vote and advised his wife, a communications staffer for Pence whom he married last year, to stay home. Kinzinger has a permit to carry a concealed weapon in the District, but almost never takes his gun to the Capitol. That day, he did.

Taking a break from the proceedings, Kinzinger left the House floor, returned to his office and started seeing incoming messages on Twitter: “@RepKinzinger we’re coming for you,” said one. “Tell us where you are right now,” said another. “I hope you know what’s coming.”

Kinzinger has long been familiar with the anger inflaming large swaths of the Republican Party’s far-right wing. He rode to Washington in 2011 on the strength of the tea party wave (Sarah Palin, fresh off her star turn as John McCain’s 2008 ticket mate, endorsed him), then annoyed tea partyers by aligning himself with GOP leadership. In turn, he was selected for choice seats on the House’s Energy and Commerce and Foreign Affairs committees. He developed a reputation for being willing to work across the aisle.

“He’s very collaborative, very expeditious,” says Rep. Marcy Kaptur (D-Ohio), with whom Kinzinger co-sponsored legislation to provide funding for European allies to invest in more secure telecom infrastructure. “I think he knows his own mind, and that’s really helpful. He’s very adroit.”

He didn’t vote for Trump in 2016. The first time he met Trump, he was visiting the Oval Office with a group of colleagues. “You’re really good on TV,” Kinzinger says the president told him. “I’m serious. You’re really good.” He says he felt like he was being worked. “I’ve seen many, many people that go in critics of Trump and come out sycophants,” he says. “Because he’s really, really good at bringing you in.”

The congressman kept his distance but toed the party line. Kinzinger’s votes aligned with Trump’s policy positions 90 percent of the time, according to FiveThirtyEight’s vote tracker. And when Democrats impeached the president the first time, for abuse of power and obstruction of Congress, he voted against it, writing, “the foundation for the articles of impeachment is weak.”

By last summer, Kinzinger was concerned enough about the baseless claims infecting large swaths of far-right Republican voters that he released multiple statements and a Facebook video debunking QAnon, an extremist ideology that portrays Democrats and anyone else who stands against Trump as part of a satanic cabal. In a tweet, Kinzinger called the online cult “a fabrication.” His statements elicited a rebuke from a Trump campaign spokesman, who responded by asking Kinzinger to denounce the Steele dossier — a collection of unsubstantiated and in some cases disproved allegations about ties between Russia and Trump or his advisers — instead.

Even still, when Trump came up for reelection last fall, Kinzinger felt secure basing his vote on the administration’s policy record. He agreed with Trump’s positions on rebuilding the military, tax restructuring and rolling back regulations. That was enough to win his vote.

But when President Biden prevailed, Kinzinger accepted the result — not just passively but out loud, on TV. When Trump posted a video in early December claiming the election was stolen, Kinzinger shot back a five-word tweet: “Time to delete your account.” Illinois political watchers wondered what his angle was.

“He was believed to be a challenger for governor against [current Illinois Gov. J.B.] Pritzker, so a lot of his early actions were seen in that lens,” says Scott Kennedy, a Democratic media consultant who runs the analytics website Illinois Election Data.

“Illinois is a tough state for Republicans,” says Walsh, the former congressman, “but Adam is the perfect kind of Republican to win statewide.”

The greater challenge might not be winning over independents or moderate Democrats in a statewide race but overcoming the fury of a Republican base that is still fiercely loyal to Trump. If those GOP voters had been willing to overlook Kinzinger’s opposition to disinformation and decertification before the attempted insurrection at the Capitol, his insistence on holding Trump accountable for the attack might be considered unforgivable. “Adam’s problem,” Walsh says, “is that because of his vote, I can’t imagine him getting through a primary.”

Kinzinger has managed to create for himself a kind of no-man’s land: a guy who supported Donald Trump’s reelection, and then voted to impeach him.

“We no longer view this as being completely calculated,” Kennedy says. “It seems highly likely he made these decisions without his immediate political future in mind.”

"Life or death, it doesn't matter," one woman reportedly declared in a video taken from the crowd outside.

Rioters overwhelmed the barricades. They fought police officers, doused them with bear spray, beat them with poles. An officer who was struck with a fire extinguisher would later die. “Hang Mike Pence!” the mob chanted as it breached an entrance.

“These are the things and events that happen,” the president tweeted, “when a sacred landslide election victory is so unceremoniously & viciously stripped away from great patriots who have been badly & unfairly treated for so long.”

This guy is done, Kinzinger thought to himself.

And yet, when order was restored and Congress continued with the certification, Kinzinger listened as members of his caucus gave speeches questioning the validity of Trump’s loss in certain states.

In the end, 147 Republicans voted to overturn the election results. A week later, 197 voted against impeaching Trump for inciting the riot. Kinzinger thinks many did so because they fear losing their seats and others because they fear losing their lives.

The line between political peril and actual bodily danger has been blurred. “Many of us are altering our routines, working to get body armor, which is a reimbursable purchase that we can make,” Rep. Peter Meijer (R-Mich.), who also backed impeachment, said on MSNBC after the attack. “Our expectation is that someone may try to kill us.”

Kinzinger says he has received multiple menacing messages since calling for Trump’s removal. “The ones I worry about are not the ones that type out a threat,” he says. “It’s the ones who just do it.” In any case, he’s confident he can handle himself.

And his political future?

Illinois’s congressional districts are likely to be redrawn in the next year, making it possible that Kinzinger will already have a harder time holding onto the Republican nomination for his current seat. And local Republicans say his votes against Trump won’t help.

“There were a lot of people who were disappointed with Adam’s remarks,” says Eli Nicolosi, chairman of the Republican Party in Winnebago County. “I think Adam knows that his opinion is his opinion alone and it doesn’t necessarily represent other Republicans. Here in Winnebago County, there are a lot of people who aren’t happy with that.”

A Republican challenger has already filed paperwork to run against him in next year’s primary. The challenger named his campaign committee “Impeach Adam Kinzinger 2022.”

Kinzinger hopes that the end of the Trump presidency will bring about an epiphany among his colleagues, that they’ll realize governing on the basis of fear and lies can hurt them more than it helps them. “Leaders have got to start telling the truth,” he says.

But he’s realistic, too. “I think we’re going to have an epic battle in the next six months for the definition of this party,” he says.

So he’ll stay and fight, function the way a soldier is expected to function.

In the end, it could cost him. But a man who already knows he’s dead doesn’t think too much about what he’s got to lose.