Some Republican senators and their advisers are privately discussing whether to pressure GOP leaders to stage a lengthy impeachment trial beginning in January to scramble the Democratic presidential race — potentially keeping six contenders in Washington until the eve of the Iowa caucuses or longer.

Those conversations about the timing and framework for a trial remain fluid and closely held, according to more than a dozen participants in the discussions. But the deliberations come as Senate Majority Leader Mitch McConnell (R-Ky.) faces pressure from conservative activists to swat back at Democrats as public impeachment hearings began this week in the House.

The discussions raise a potential hazard for the six Democratic senators running for president, who had previously planned on a final sprint out of Washington before the Feb. 3 Iowa caucuses and the Feb. 11 New Hampshire primary.

“That might be a strategy,” Sen. Ron Johnson (R-Wis.) said with a coy smile when asked about the possibility of a trial that disrupts the Democratic campaign. “But I’ll leave that up to others. I’m just a lowly worker.”

Sen. John Cornyn (R-Tex.), a McConnell ally, said the Senate would try to distinguish itself during impeachment “by doing this right,” with a trial that probably lasts five or six weeks. But he acknowledged the timing could have an effect on the campaign by giving a potential boost to presidential candidates who have no official role in the process.

“Pete Buttigieg and Joe Biden might like that,” Cornyn said of the mayor of South Bend, Ind., and the former vice president, who now poll in the top four in Iowa with Sens. Elizabeth Warren (D-Mass.) and Bernie Sanders (I-Vt.).

There is an emerging divide among Republicans, however, over timing. While some Republicans favor a lengthy trial as a means of defending President Trump and creating problems for Democrats, others are calling for swift dismissal or final vote.

The Democratic senators who remain in the presidential race have all said publicly that the impeachment proceedings are more important than political concerns. But advisers to multiple candidates have been inquiring about the potential timing behind the scenes, and Sanders has spoken about the potential challenges of an extended trial if the Democratic-controlled House votes to impeach Trump and sends the case to the Senate.

“We will do our best to get back to Iowa, to get to New Hampshire, to get to all the states that we have to,” Sanders said Sunday at an event in Charles City, Iowa, when asked about a potential trial in January. “But there’s no question it will make our life a little bit more difficult.”

Warren said Wednesday that she has “constitutional responsibilities” and “if the House goes forward and sends impeachment over to the Senate, then I will be there for the trial.”

One top adviser to a senator running for president, who spoke on the condition of anonymity to discuss strategy, said the campaign was already rearranging fundraising and campaign schedules to prepare for a trial.

“We’ve been all but told that January is when we should expect not to have them,” the person said. “And that in December is when we should expect to have them.”

The issue of trial length came up during a closed-door lunch of all GOP senators Wednesday, when Republicans speculated about whether the House would hand over the process to them either before or after Christmas, according to multiple people in attendance.

Inside the lunch, McConnell had little guidance for his ranks, outside of saying the trial will go on as long as the Senate wants it to run, said the people, who spoke on the condition of anonymity to share details from the private meeting.

But McConnell’s deputies, as well as most of his ranks, believe a longer trial is the likelier outcome — which they say would give Trump and his defense team sufficient time to make his case.

Cornyn said Wednesday that it would be difficult to find a majority in the Senate to dismiss the trial early on, even if the president’s attorneys request it, “before the evidence is presented.”

“I think the consensus in our conference is at least that we need to proceed and take seriously the responsibility we have,” said Sen. John Thune (S.D.), the second-ranking Senate Republican. “How long that takes is an open question . . . but I suspect that, you know, it’d go on for a while.”

Sen. Richard Burr (R-N.C.), who has speculated publicly that a Senate trial could run as long as eight weeks, argued during the lunch that former president Bill Clinton’s impeachment proceedings in the Senate took five weeks but that Trump’s case was likely to take more time because he has not admitted to any wrongdoing.

Clinton “admitted that he had lied to the FBI,” Burr said before the lunch. “I figured it’s going to take longer for them to make a case, because they don’t have that.”

One White House official said the president is not yet concentrating on a trial but has spoken with McConnell, Vice President Pence and Sen. Lindsey O. Graham (R-S.C.), the chairman of the Judiciary Committee, about the outlook in the chamber. Newly hired White House aides who are working on impeachment issues have also been meeting with Senate GOP staffers this month.

McConnell has not publicly committed to a timeline for a trial. “I think it’s impossible to predict how long we’ll be on it or predict which motions would pass,” the GOP leader said Wednesday.

But McConnell will not be able to set the schedule in isolation. The rules for an impeachment trial, including a process for calling witnesses, must be passed by 51 or more senators, since Pence is not able to cast a deciding vote on the question. That gives McConnell, who oversees a 53-seat Republican majority, relatively little room to maneuver.

Sen. Mitt Romney (R-Utah) has been a sharp critic of Trump’s behavior on Ukraine, and more independent-minded senators, like Lisa Murkowski (R-Alaska), could side with Democrats to force a process that Democrats accept as fair, according to a person familiar with Republican discussions.

A separate group of centrist Senate Republicans facing tough reelection fights next year have been telling McConnell and colleagues that they do not want the process to be rushed, worrying that any move to quickly dispense with a trial risks giving their Democratic opponents an opening to say they did not take their duties seriously.

That view has been bolstered by Sen. Mike Lee (R-Utah), who has privately told conservative colleagues they must give breathing room to Republicans running in 2020 and let the trial play out for at least a few weeks, according to two Republican aides briefed on the talks, who spoke on the condition of anonymity to discuss the internal deliberations.

“This is going to require a great deal of work, and I don’t think it should be rushed through,” said Sen. Susan Collins (R-Maine), who is up for reelection in 2020. Collins said any attempt to dismiss impeachment at the outset of a trial would be met with vocal opposition by a “lot of senators, who’d have misgivings and reservations about treating articles of impeachment that way.”

On the other hand, several Trump allies are planning to prepare a motion to dismiss that they could propose early on during a trial.

“The sooner we’re done with this, the better,” said Sen. Rand Paul (R-Ky.). “Why just have people sitting around for this partisan sham? As soon as we possibly can dismiss this or vote along party lines, especially if the Democrats in the House limit the witnesses, I’ll move to do that.”

Sen. David Perdue (R-Ga.) also dismissed the prospect of a lengthy trial, saying a “week is more than enough.”

Senate Minority Leader Charles E. Schumer (D-N.Y.) has been talking with Democratic senators, including those running for president, to decide the best way to approach any negotiation with McConnell about whether Democrats join in a resolution setting up the Senate process.

“Given articles of impeachment haven’t even been drafted, it’s impossible to know what either side would want a trial to look like,” said a person familiar with Schumer’s thinking, who spoke on the condition of anonymity to discuss strategy. Schumer declined Wednesday to discuss his next steps but warned that a trial should not be “truncated.”

McConnell’s general template remains the Senate impeachment trial of Clinton in early 1999, which lasted five weeks and had a bipartisan consensus at its start about how it would proceed, according to McConnell’s aides and allies.

Discussions on Senate rules in 1999 broke down repeatedly before the chamber finally agreed on a compromise by a margin of 100-to-0.

An initial proposal by Sens. Joseph I. Lieberman (D-Conn.) and Slade Gorton (R-Wash.) to make a full trial contingent on a two-thirds supermajority finding Clinton’s alleged offenses impeachable faced fierce objection from Republicans.

“When I presented it to the Republican conference, they did everything but stone me and throw me out in the hall,” said former senator Trent Lott (Miss.), who was then the Republican leader.

A compromise was reached later in a closed-door meeting for all senators in the Old Senate Chamber, when Sens. Phil Gramm (R-Tex.) and Edward M. Kennedy (D-Mass.) agreed they should start the trial before deciding whether witnesses would be called before the full body.

Lott said McConnell and Schumer might have a more challenging time striking a deal.

“This is a different situation,” he said. “You do have a divided Congress. You do have a president who has agitated a lot of people.”

Sean Sullivan and Rachael Bade contributed to this report.