Now that former President Donald Trump has been acquitted for his role in inciting the Jan. 6 riot at the Capitol, Sen. Lindsey Graham (R-S.C.) has a warning for Democrats: When and if Republicans regain control of Congress — perhaps as soon as 2022 — they might be happy to let a thousand impeachments bloom.

"If you use this model, I don't know how [Vice President] Kamala Harris doesn't get impeached if the Republicans take over the House, because she actually bailed out rioters and one of the rioters went back to the streets and broke somebody's head open," Graham said Sunday on Fox News. "So we've opened Pandora's Box here, and I'm sad for the country."

Nobody really believes Graham's more-in-sorrow-than-in-anger routine at this point, but his comment — threat, really — is ridiculous on its face. Republicans have just 50 Senate votes now; an impeachment conviction takes 67 votes. Even if the GOP somehow wins every one of the 14 Democratic seats open in 2022, that still wouldn't be enough to sustain a conviction. And Graham's scenario assumes that GOP leaders would happily risk the political blowback that would surely come from a nakedly frivolous impeachment launched simply to avenge Trump.

But Graham isn't the only observer to suggest American politics is in danger of a cycle of frequent and unnecessary impeachments, both of current and former officials. Take Sen. Jerry Moran (R-Kan.), who on Saturday justified his vote to acquit Trump by expressing concern that doing otherwise would put a metaphorical bullseye on every former president.

"Establishing the precedent that the Senate has jurisdiction to convict a former president would cause extreme damage to our country and the future of the presidency," he said in a written statement.

To which the proper response is: Hey, if Jimmy Carter someday inspires a deadly insurrection at the Capitol in order to seize power by overturning the legitimate results of an election, by all means go ahead and impeach him.

Not all potential impeachments are equal, of course.

Graham isn't wrong to suggest that impeachments are partly the result of opportunity. Trump probably never would have been impeached once — let alone twice — if Democrats hadn't won control of the House of Representatives in 2018. It is also true, though, that Trump was impeached for doing extraordinarily bad, selfish things.

Remember, House Speaker Nancy Pelosi (D-Calif.) spent most of 2019 resisting calls from her caucus to impeach Trump, proceeding only after the emergence of whistleblower accusations that he used his authority to pressure Ukraine's government into undermining Joe Biden's presidential campaign. And she launched the second impeachment because Trump — in front of the whole world, via television and Twitter — inspired the Capitol riot by spending months repeating the lie that he won the 2020 election by a landslide.

Similarly, Richard Nixon was nearly impeached in 1974 — he resigned instead — because he misused the power of the presidency against his political enemies. The closest thing we have had to an unreasonable impeachment in living memory came during the 1990s, when Bill Clinton was tried by the Senate for lying under oath about his affair with Monica Lewinsky. Graham, not incidentally, was a House impeachment manager in that case.

It can be argued that most presidents get around to committing a high crime or misdemeanor during their term in office. Just in this century, George W. Bush authorized the torture of terror suspects and warrantless surveillance of Americans, while Barack Obama controversially had an American terror suspect executed by drone attack. Those were terrible acts, but they at least were arguably undertaken in the name of American national security, on behalf of the citizenry.

So it isn't the case that simple policy differences, or mere politics, have been criminalized by the impeachment process. Trump wasn't put on trial for bypassing Congress to build his border wall. Nixon wasn't forced from his job because he bombed Cambodia. In both cases, they faced impeachment precisely because they abused their authority to benefit themselves and their own political purposes.

If Republicans want to be reasonable, that will be the precedent they take from this last sordid year, and not simply that it is possible to impeach a president for any old reason just because you have majorities in Congress. Of course, reason appears to be in short supply within the GOP these days. But if frivolous impeachments become de rigueur the next time the party takes power, it will not be because Democrats opened Pandora's Box — it will be a conscious choice by Graham and his Trumpist cronies.