The Mueller report was too much of a letdown. True, that was in part because of the artful deception by Trump’s attorney general, William Barr, in releasing the report — but only in part. Over all, the report was anticlimactic. It persuaded virtually no one who wasn’t already persuaded of Trump’s unfitness.

If the Democrats had impeached him after the report’s release — after specifically saying that they would make their decision based on the report — they would not have persuaded many swing voters (or virtually any Republicans). I understand that many progressives wanted House Democrats to impeach Trump anyway, as a matter of principle. But I think that view overlooks the history and purpose of impeachment: It is, again, a political process.

If you impeach a president and fail to damage his political standing — if you’re just as likely to shore up his standing, as I think a post-Mueller impeachment would have — you’re doing it wrong. You are going to political war with the Constitution you want rather than the one the country has.

Many House Democrats understood this. They’ve certainly made mistakes since retaking House control this year — namely, failing to hold investigative hearings that might have shifted public opinion. But Democrats were right to reject calls for impeachment. Most House members who represent swing districts were right about this, and so was Nancy Pelosi.

And they are right to be changing their minds now.

Starting an impeachment inquiry is the proper move because of both what’s changed and what hasn’t. What has changed? In his dealings with Ukraine, the president committed a new and clearly understandable constitutional high crime: He put his own interests above the national interest by pressuring a foreign country to damage a political rival. He evidently misused taxpayer money in the process. He has shown he’s willing to do almost anything to win re-election.