With Trump’s Trial Over, Lawmakers Ponder How to Conduct the Next One

WASHINGTON — The bruising fight over President Trump’s impeachment may be over, but in the Senate, the fight over how to conduct the next one — of him or a future president — is just beginning.

Republicans want to make it more difficult to impeach and try a president for high crimes and misdemeanors, while Democrats are working to require that any such trial allow new evidence, including the kind of witness testimony and documents that Republicans voted to block from being considered before rendering a verdict on Mr. Trump.

The dueling proposals reflect the polar opposite stances of the two parties on Mr. Trump’s impeachment, but they also underscore deep worries among Republicans and Democrats alike that the exercise is likely to become more frequent, given persistent and intense partisanship.

One top Republican official said privately that the Senate should consider instituting a way to filter out “nuisance” impeachments rather than allow the Senate to be automatically plunged into a full-blown trial once charges are delivered by the House in a ceremony the official described as akin to a visit from the three Magi.

Senator Rick Scott, Republican of Florida, is proposing a constitutional amendment to raise the voting threshold for passing articles of impeachment in the House to three-fifths, from a simple majority, because of what he saw as a partisan attempt to impugn Mr. Trump.

On the Democratic side, Senator Jeff Merkley of Oregon wants to institute a rule that would guarantee new witnesses and documents to be allowed, after Republicans led by Senator Mitch McConnell of Kentucky, the majority leader, thwarted Democratic attempts to do so. Senator Chuck Schumer of New York, the Democratic leader, endorsed the concept.

“I’d like to see witnesses and documents be required,” Mr. Schumer said.

Senator Josh Hawley, Republican of Missouri, wants to “deem” any House-passed articles of impeachment as sent to the Senate within a certain time period even if the House does not formally send them — a response to Speaker Nancy Pelosi’s decision to sit on the House-passed accusations against Mr. Trump for weeks. Republicans saw that as an unacceptable attempt by the House to dictate to the Senate the trial’s timing and ground rules.

“There ought to be some way to get the trial started, you would think, short of the physical papers being delivered,” Mr. McConnell, who supports Mr. Hawley’s idea, said in an interview.

Despite dissatisfaction in both parties about how parts of Mr. Trump’s trial unfolded, some senior lawmakers warn that the Senate should not act hastily in making underlying changes to the rules when emotions remain raw. One lawmaker’s nuisance impeachment would no doubt be another’s necessary one.

“We have to give it a pretty significant cooling-off period before getting back into how these rules should work,” said Senator Roy Blunt, Republican of Missouri and the chairman of the Rules Committee. He noted that considerable time passed between Congress gearing up for the 1974 impeachment trial of President Richard M. Nixon — which never happened because Mr. Nixon resigned before the House moved forward with his impeachment — and the adoption in 1986 of the current impeachment rules.

“They waited a dozen years before they said, ‘OK, now that things have totally settled down, nobody has an ax to grind, half the Congress that was here in 1972 isn’t here anymore, let’s look at the rules,’” Mr. Blunt said.

The nature of the changes being proposed could bolster Mr. Blunt’s call for time to pass, since the primary ones seek to correct what each party saw as an injustice at the hands of the other.

Mr. Scott’s plan to require a supermajority impeachment vote in the House takes aim at the successful party-line push by House Democrats to impeach Mr. Trump without a single Republican vote — an outcome that would have fallen far short of the three-fifths standard.

“An act as divisive as impeachment must have bipartisan backing and overwhelming support,” Mr. Scott said in a statement, adding that trying to oust the president “should be harder — much harder.” But his proposal might be the hardest to achieve since it would require a constitutional amendment — a time-consuming route that rarely results in success — while others could be accomplished through either legislation or changes in Senate rules.

Democrats say the refusal of Republicans to allow new witnesses was a fundamental flaw in the trial that should be corrected.

“The Senate must never fail its constitutional responsibility in this manner again,” Mr. Merkley said. Republicans who viewed the witness push as a tactic to extend the trial and unnecessarily tie up the Senate are highly unlikely to back the Democratic push for witness guarantees — though their minds might change if the impeachment tables were turned.

In addition to altering some of the finer points of the rules, there is the question of whether the modern Senate is a cultural fit for the sort of impeachment trial envisioned by the authors of the Constitution. No doubt, they imagined senators sitting silently — uninterrupted by the thrum of digital inputs on electronic devices or the demands of a 24-hour cable television news cycle — through hours of presentations, and then delivering a well-reasoned verdict at the conclusion.

Instead, restless senators, accustomed to constantly checking their phones, conferring with staff and spending little time on the floor, fidgeted through the proceeding, appearing by turns exhausted and frustrated, as the trial consumed hour after hour even though the result was preordained. Republicans accused House prosecutors of taking advantage of the opportunity to continuously repeat their case to reach a television audience rather than to persuade senators of the president’s wrongdoing.

“You had about 45 minutes of presentation that the House managers presented about 45 times,” Mr. Blunt said. “At some point, there is disrespecting your colleagues. Not only did we get restless, we got resentful.”

Still, it would be hard for senators to justify rule changes that would give impeachment short shrift in favor of scrolling through Twitter and Gmail.

“I think sitting there and having to listen is probably a good thing,” Mr. Schumer said. “I feel very strongly that when your are impeaching a president you should have to be there. You should not be looking at your Blackberry or your iPhone.”