The violence that Americans witnessed—and that might recur in the coming days—is not a protest gone awry or the work of “a few bad apples.” It is the blossoming of a rotten seed that took root in the Republican Party some time ago and has been nourished by treachery, poor political judgment, and cowardice. When Trump leaves office, my party faces a choice: We can dedicate ourselves to defending the Constitution and perpetuating our best American institutions and traditions, or we can be a party of conspiracy theories, cable-news fantasies, and the ruin that comes with them. We can be the party of Eisenhower, or the party of the conspiracist Alex Jones. We can applaud Officer Goodman or side with the mob he outwitted. We cannot do both.

If and when the House sends its article of impeachment against Trump to the Senate, I will be a juror in his trial, and thus what I can say in advance is limited. But no matter what happens in that trial, the Republican Party faces a separate reckoning. Until last week, many party leaders and consultants thought they could preach the Constitution while winking at QAnon. They can’t. The GOP must reject conspiracy theories or be consumed by them. Now is the time to decide what this party is about.