Senator Ben Sasse sat perched on a stool, decked out in a bright red Nebraska Cornhuskers’ tracksuit. Smile wide, brown hair swept back, the Nebraska conservative glanced back-and-forth between the camera and his gold iPhone as he read messages from his Twitter feed:   

“ ‘@BenSasse, Senator you are an embarrassment to your constituents and a jackass.’ ”

“ ‘Ben Sasse is a joke, looking for a punchline! What a maroon!’”

“’ Senator Sasse, you’re a douchebag. When Trump because [sic] president, your days will be numbered.’ ”

“ ‘Ben Sasse: Can anyone believe this bozo is a U.S. Senator?’ ”

Here, Sasse paused to joke: “My brother says this every week.”

“ ‘Ben Sasse. Shut up loser Sasse! How much you get for votes this year so far dead beat! Nobody believes anything you say.’ ”

“ ‘Why does media allow biblical donkey hole @BenSasse to continue trolling #Trump?’ ”

And on the short, saucy video rolled, with Sasse cracking up now and then as he shared some of the heartfelt feedback he has received regarding his prominent role in the #NeverTrump movement.

Even as Donald Trump’s campaign rallies devolve into a cross between a pro-wrestling match and a Klan march, many Republican lawmakers remain too chicken to take a stand against the aspiring despot. (Asked Sunday about his earlier pledge to support Trump if he won the nomination, Marco Rubio could only waffle, “It’s getting harder by the day to justify.”) Oh, sure, plenty of members are rooting for Trump to fail, but few are willing to take him on publicly. In the Senate, only Sasse has gone so far as to vow that, if Trump is his party’s pick, he will not back him. Indeed, for months now, Sasse has been actively working against Trump’s candidacy, lamenting it as part of a larger constitutional crisis threatening American democracy. It is a mini-crusade that has turned him into a hero for many Trump-phobic conservatives—including a chunk of the conservative media—and a prime target for Trump fans.

Sasse’s highest-profile slap at Trump came late at night on February 28, when he posted “an open letter to Trump supporters” on Facebook, explaining why he could not support their guy. It was a long, impassioned discourse on American exceptionalism, the role of political parties, constitutional restraint, and other grand concepts that ultimately boiled down to: “he displays no understanding of the fact that, in the American system, we have a constitutional system of checks and balances… have you noticed how Mr. Trump uses the word ‘Reign’—like he thinks he’s running for King? It’s creepy, actually.”

Sasse’s letter hit the same day that Trump refused to disavow David Duke and the Ku Klux Klan on CNN. This was not a coincidence. “I had probably been [thinking this way] a number of weeks,” says the senator, whose has urged conservatives to seek a third-party alternative if Trump is the nominee. Trump’s “playing footsie with David Duke had me speak out when I did.”

The social-media strike promptly threw Sasse into the spotlight, as mainstream outlets from The Washington Post to CNN to the Huffington Post to The New York Times to Esquire took note. On March 3, a new PAC popped up aimed at drafting Sasse to run for president as a third-party candidate. Quick as a snake, the senator shot down the idea. Still, not bad for a guy who, as he likes to point out, is 99th in seniority in the upper chamber.

Not that Sasse had been coy about his feelings before this. In a December speech of the Senate floor, he called Trump “a megalomaniac strongman.” In the run-up to the Iowa caucuses, Sasse traveled to Iowa to speak out against the celebrity mogul. Also in late January, the senator released a tweet storm of awkward questions about Trump’s past political positions, provoking a rage-filled backlash. That was when Sasse’s two daughters, ages 12 and 14, “hatched the idea” of a video of their dad reading mean tweets from Trump supporters as a kind of “therapy” for the family, he tells me. “My daughters had just seen a ton of stuff, and a little bit of it unsettled them.” (The resulting “U.S. Senator Ben Sasse Reads Mean Tweets from Trump Supporters” video was put together with the help of Independent Journal Review, the conservative viral-news site that also created “How to Destroy Your Cell Phone With Lindsey Graham.”)

Along the way, Sasse has emerged as something of a rockstar in the conservative media. In the past couple of months he has enjoyed approving coverage in National Review and the Weekly Standard, a flattering sit down with the Heritage Foundation’s Daily Signal, and lavish praise on RedState.com. The Blaze has been following his activities closely, including a moment at this month’s Conservative Political Action Conference when Sasse confronted Fox News’ Sean Hannity at this month’s to call “bull” on Hannity’s assertion that Sasse’s opposition to Trump amounted to a vote for Hillary Clinton. A post introducing his radio interview on GlennBeck.com praised him for “taking a lot of heat for saying something very brave.”

Sasse says he’s hearing from a lot of conservatives, big-name commentators and garden-variety voters alike, grateful for the stand he has taken. Many of these folks can be found on his twitter feed—alongside the ongoing stream of abuse from pro-Trumpers, accusing him of being everything from a RINO to a pedophile.

As the Trump circus threatens to spiral out of control, Sasse has no intention of toning down the criticism. When he and I spoke Friday, he expressed dismay at how the question of growing violence at Trump rallies had been soft-pedaled at the previous evening’s debate. “I was stunned that when the question was asked, Trump didn’t condemn the violence,” Sasse told me. “He just said, ‘Well, I hope I haven’t done anything to cause it.’ How did the panelists running the debate not follow up and ask about Trump’s campaign manager bruising a [Breitbart News] journalist and then, after the fact, saying, ‘I didn’t know what outlet she was with. I didn’t know it was an outlet we had decided to rent for a year.’”

Sasse doesn’t blame Trump alone for turning the Republican primary into a violent freak show, and he credits the billionaire with recognizing how out-of-touch the GOP has become with its voters.  “I think party is in deep, deep trouble regardless of what happens next with Trump,” said Sasse. “He was only able to wage a hostile takeover because the Republican Party was so terribly vacuous.”

Whatever the circumstances that brought Republicans to this point, Sasse is determined to do all he can to stop the madness. “American greatness isn’t about one guy’s ego and bluffing claims to do everything unilaterally,” he said. “It is about the rule of law, not the rule of a strongman.” Sadly, he said, “we have a front-runner who just doesn’t get it.” And if voters aren’t careful, Sasse fears, Trump could wind up taking down more than just the Republican Party.