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Impeachment is an inherently political process. The framers designed it that way. It is the ultimate way that one branch of the federal government can hold another branch accountable.

Impeachment is not like a criminal trial, in which a jury or judge is supposed to base a verdict only on what happens inside the courtroom. The Constitution’s standard for impeachment — “high crimes and misdemeanors” — is deliberately vague. The decisions about whether the House should impeach and whether the Senate should convict have always involved a mixture of law, politics and public opinion.

For this reason, I have long thought Democrats would be making a mistake by starting impeachment proceedings against President Trump, even though I also believed Trump was manifestly unfit for office.

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.

What hasn’t changed? Trump is unfit for office. He has repeatedly violated his oath of office, to preserve, protect and defend the Constitution. He has weakened America’s national security. He has used the presidency for personal enrichment. He has broken the law more than once. He has tried to undermine American democracy.

Trump has handed Democrats a new opportunity to persuade the country that his presidency needs to end, on Jan. 20, 2021, if not sooner. Democrats should seize that opportunity. Even if they can’t persuade Republican senators to remove him from office, they can focus voters’ attention on his egregious misbehavior.

It’s time to start an impeachment inquiry and see where it leads.

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