WASHINGTON — The second season of impeachment had ended less than a day earlier, but Republicans were already talking about next season. It sounded ominous.

“I don’t know how Kamala Harris doesn’t get impeached if the Republicans take over the House,” Senator Lindsey Graham, Republican of South Carolina, said Sunday morning on Fox News.

Mr. Graham seemed to be suggesting that the vice president might be punished because she had expressed support for a bail fund for Black Lives Matter protesters in Minnesota last summer. “She actually bailed out rioters,” Mr. Graham charged. That statement was false, but his threat was plain: Republicans can impeach, too.

In recent days, former President Donald J. Trump’s defenders have darkly accused Democrats of opening a “Pandora’s box” of partisan retribution — leading to a kind of anything-goes future in politics, where impeachments get volleyed back and forth between the two parties like a tennis match, depending on which side controls Congress. “Partisan impeachments will become commonplace,” said Bruce L. Castor Jr., one of Mr. Trump’s lawyers, as he argued the former president’s case before the Senate on Tuesday.

There’s an element of plausibility here, given the hyperpartisan fervor that’s gripped American politics. But in the ensuing environment, Republicans seem to be saying that even the most outlandish accusations against a president — such as those hurled at President Biden by Representative Marjorie Taylor Greene, a Republican of Georgia in her first days in Congress — should be treated the same as what Democrats impeached Mr. Trump over.

In a broader sense, officials of both parties have suggested that regular impeachments may just become one of several regular features of a new and bitter normal in our politics. Previously rare or unthinkable measures could simply start happening all the time

Democrats argue that, in fact, Republicans have opened several Pandora’s boxes in recent years. They have taken unprecedented actions, led by Mr. Trump, that have abused certain norms to a degree that has destabilized a set of once-reliable government traditions. Senate Republicans’ blockade of President Barack Obama’s nomination of Judge Merrick B. Garland to the Supreme Court in 2016, for instance, cast doubt on any future president’s ability to fill a Supreme Court vacancy when the opposing party controlled the Senate.

By refusing to concede an election he clearly lost, and then maintaining repeatedly it had been stolen from him, Mr. Trump shattered what had been an undisturbed American custom ensuring a peaceful transfer of power between administrations.

Mr. Trump’s false claims have persuaded a majority of Republican voters that Mr. Biden had not been legitimately elected, and led 147 Republican members of the House and the Senate to vote against the Jan. 6 certification of Electoral College votes. This level of support to overturn the election result raises the prospect of whether the once-pro forma exercise of certification might now devolve every four years into a heated partisan spectacle — or, worse, riots.

It was the deadly assault on the Capitol, of course, that set into motion Mr. Trump’s second impeachment proceeding. His lawyers attributed the rebuke not to their client’s actions on Jan. 6 but rather to his opponents’ irrational “hatred of President Trump.” They implied impeachment was a vindictive and frivolous maneuver.

Democrats bristle at such notions — that they have overused and thus cheapened the power of impeachment, a tool that has been employed only four times in 244 years, but twice in the last 14 months. They agreed that impeachment should be reserved for extraordinary circumstances, but argued that Mr. Trump had engaged in an extraordinary degree of dereliction.

“Look, there’s a reason there’s been two impeachments of the same man,” said Senator Robert P. Casey Jr., Democrat of Pennsylvania, in an interview Friday, on the eve of the final vote. “Trump has engaged in conduct that presidents of either party would never engage in.”

It’s not like anything about this has been fun, he added. “The last thing I wanted to do these last five days is sit there and listen to this hour after hour instead of working on a full range of issues,” he said.

Mr. Casey and others suggest that the Republican Party is now dominated by a former president who has convinced much of the party that any opposition to them is driven by “bad, sick and corrupt people” and should be met with extreme tactics.

“The expectation from our base is for retribution,” said former Representative Tom Rooney, a Republican of Florida who did not seek re-election in 2018, in part to escape the extreme partisanship that has overtaken Congress. When asked if his former Republican colleagues would move to impeach Mr. Biden next year if they won back the House, even for something minor, Mr. Rooney rated the prospect as “absolutely possible.”

“It might not necessarily be what some of those guys want to do, but it might be what the base expects,” he said. “People want Armageddon.”

Let the healing begin!

Or not. For as much as Impeachment II ended on Saturday with a significant number of Republican senators (seven) voting to convict Mr. Trump — and was accompanied by tough statements from some who voted not guilty, including the Republican Senate leader, Mitch McConnell — other defenders of the former president turned their focus to a bitter future of impeachment roulette.

Senator Marco Rubio, Republican of Florida, suggested on Friday that former Secretary of State Hillary Clinton might start looking around for a good impeachment lawyer (because, really, what would partisan Armageddon be without the Clintons?).

Mr. Rubio framed his statement around a somewhat tortured rhetorical question: “Is it not true that under this new precedent, a future House facing partisan pressure to ‘lock her up’ could impeach a former secretary of state and a future Senate forced to put her on trial and potentially disqualify from future office?”

It was not exactly clear whether Mr. Rubio was criticizing Mr. Trump for whipping up his supporters into a frenzy that led to irrational demands to imprison Mrs. Clinton, or whether he was accusing Democrats of acting irrationally themselves by impeaching Mr. Trump a second time in two years.

What was evident, however, was that Mr. Rubio was assuming the worst intentions by the opposition — and the feeling appears extremely mutual. Cable and social media chatter have been awash in bleak scenarios.

“If Republicans take Congress, they could not only impeach Biden and/or Harris,” Jon Favreau, a speechwriter for President Obama, tweeted on Sunday, “they could potentially succeed in overturning the results of the 2024 election.”

Not everyone believes partisanship has reached the point where Election Day will now merely become the start of a two-month brawl every four years that will build to a potentially ugly climax in January.

“I don’t think we’re there yet,” said Brendan Buck, a Republican media strategist and former top leadership aide to two former Republican speakers of the House, Paul D. Ryan of Wisconsin and John A. Boehner of Ohio. He said that many House Republicans wound up voting against Mr. Biden’s Electoral College certification only because they knew it would not pass. If the result was more in doubt, he contended, they would have voted to certify.

Still, Mr. Buck allowed that the current political and media environment rewarded behavior by lawmakers — and candidates — that is extreme or even unheard-of. “We’re in an era where you need to make loud noises and break things in order to get attention,” he said. “It doesn’t matter what you’re breaking — as long as you’re creating conflict and appeasing your party, anything goes.”

Mr. Trump himself is the exemplar of anything goes, both in terms of how effective and destructive the approach can be, said Adam Jentleson, who was a deputy chief of staff to former Senator Harry Reid of Nevada, the Democratic leader, and author of “Kill Switch: The Rise of the Modern Senate and the Crippling of American Democracy,” a new book about legislative leadership dynamics.

Mr. Jentleson said Republicans had abandoned any coherent policy goals in lieu of pursuing a “negative partisanship” agenda — which he defines as “doing simply whatever will terrorize your opponents the most.” In essence, Trumpism.

This shows no signs of abating anytime soon. “That’s clearly what Republicans will continue to run on,” Mr. Jentleson said. “And that includes impeaching whoever is in power on the other side.”