The era of negative partisanship in a nutshell: “The main thing the Democrats are for is being anti-Republican and anti-Trump and the main thing Republicans are for is being anti-Democrat and anti-CNN.”

That sentiment will help seal his doom if he runs for reelection in 2020, though. Rule one in American politics 2018: If you’re not on the team, you’re against it. By his own admission, Sasse isn’t on the team. He reiterates here something he’s said before, that he thinks of himself as an “independent conservative” who caucuses with Republicans. (The right-wing Bernie Sanders?) He affirms for Tapper what he said on Twitter yesterday, that he thinks about formally leaving the party every day. Only a man who’s already resolved not to run for reelection or who’s completely indifferent to whether or not he wins would utter heresies like that on camera, knowing how they’ll be used against him in a Senate primary.

But maybe Sasse thinks there’s no point pulling his punches at this late hour. He’s antagonized Trump and Trumpers so many times over the past three years that there’s no avoiding a primary challenge now. Besides, when push comes to shove, they don’t really care about his loyalty to the GOP. They care about his loyalty, or lack thereof, to Trump. Being a loud-and-proud party guy who votes with the president 98 percent of the time or whatever won’t absolve him of that unforgivable sin. Only kissing the president’s ass will, and Sasse isn’t obviously prepared to do that. Thank God — the Senate has enough Lindsey Grahams already.

Sasse spends much of his time here lamenting how bogged down Washington is in Trumpian drama and partisan mud-flinging nonsense instead of talking about the storm of crises in labor and foreign policy that’s gathering, which is fair enough. (“It’s pretty clear that this White House is a reality show, soap opera presidency,” he said elsewhere this morning.) But he himself devotes an unusual percentage of his face time with the public dwelling on that nonsense; if you were asked to say what you think of when you think of Ben Sasse, you’re more likely to recall a moment when he flayed Trump or excoriated the Senate for its latest SCOTUS-hearing embarrassment than a policy proposal he advanced, a weird-but-true fact about a guy who’s constantly demanding a more substantive politics. There are various grounds on which he might be excused for that: He’s a junior, first-term senator and thus rarely in a position to move legislation; his preoccupation with Washington’s civic collapse is a meta-problem that must be solved before any policy challenge can; and his shots at Trump and his colleagues are more often accurate than not. Yet the fact remains that his political identity, at least at this moment, is mainly as a sort of hall monitor for the Senate, not as a problem-solver. No wonder he’s not eager for a second term.

Tapper asks him if there’s any chance that he’ll primary Trump, by the way. He does not rule it out.