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 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.