More than half of the five top-polling candidates competing in the Iowa Democratic caucuses are preparing to close out the campaign exactly where they never hoped to be — 1,000 miles away on the floor of the U.S. Senate, acting as jurors in the impeachment trial of President Trump.

The situation will put to a test the operations that Sens. Bernie Sanders (I-Vt.), Elizabeth Warren (D-Mass.) and Amy Klobuchar (D-Minn.) have put together in the state, as they are forced to temporarily abandon the face-to-face campaigns that define Iowa politics and instead lean heavily on surrogates, campaign staff and ads.

Warren plans to send her husband and supporters such as former housing secretary Julián Castro and Rep. Katie Porter (D-Calif.), while Klobuchar has announced she will dispatch her husband and daughter Abigail, along with Minnesota and Iowa politicians who have endorsed her. Sanders is also expected to dispatch supporters to campaign in his stead.

The two other top candidates in the Feb. 3 caucuses besides Sanders and Warren — former vice president Joe Biden and former South Bend, Ind., mayor Pete Buttigieg — are positioning themselves to capi­tal­ize on their rivals’ absence. Both have planned a heavy schedule in the state while their rivals are away.

“I’d rather be in Iowa today. There’s a caucus there in two and a half weeks. I’d rather be in New Hampshire and Nevada and so forth,” Sanders told reporters Thursday in the U.S. Capitol. “But I swore a constitutional oath.”

Buttigieg’s campaign has argued that staying out of the polarized impeachment conversation will bolster his pitch as the candidate who can mollify partisan tensions and disrupt the traditional Washington ways of doing things. He held five events in Iowa on Thursday, as the Senate impeachment proceedings began, and has planned another five town halls on Tuesday and Wednesday of next week, during the initial phase of Senate trial arguments. Biden will also host events in the state during those days.

After playing defense in the early days of the impeachment saga, Biden’s campaign has recently pivoted to embrace its complicated presence, arguing that the president’s alleged efforts to find disparaging information on the Biden family in Ukraine is a reflection of the candidate’s strength, not evidence of a potential weakness.

“Trump knows Biden can beat him in Pennsylvania, Michigan and Wisconsin,” the narrator declares in a Biden campaign ad that features the president repeatedly saying his name.

Warren has so far dealt with the impeachment question by saying, “There are some things more important than politics.” But she could still try to find political advantage in the trial by using Trump’s alleged misdeeds to pivot back to the campaign theme with which she began her race: fighting corruption in politics.

Sen. Michael F. Bennet (D-Colo.), the fourth senator running and the only one focused distinctly on New Hampshire, will also be grounded for key days before that state’s primary on Feb. 11. Like others, his campaign is planning satellite and radio interviews in the early primary states to keep in the mix.

The danger of spending time away from Iowa may be greatest for Klobuchar. Unlike Sanders and Warren, who have spent months building prodigious organizations, she has a smaller operation and is still polling under the crucial 15 percent threshold necessary for winning delegates in Iowa. A strong showing there, next door to her home state, is critical for her hope to move forward.

Her campaign is trying to plan events that she can call into via Skype, or telephone-based town halls where supporters can hear from her directly.

Like the other senators, she also plans to spend as much time as possible on national television speaking about the impeachment trial from Washington, hoping that the message will break through to caucus voters.

“What remains to be seen and known is just what this will look like on television in Iowa,” said one Klobuchar adviser, who spoke on the condition of anonymity to discuss campaign strategy.

There is still no certainty that the trial will even finish before the caucuses. Senate Majority Leader Mitch McConnell (R-Ky.) has pledged to use as a blueprint the 1999 impeachment trial of President Bill Clinton, with the senators working every day but Sunday and taking Martin Luther King Jr. Day as a holiday.

That trial set aside three days for House prosecutors to present their case, three days for a White House defense, and three days for Senate questions and answers before debate and a vote on a motion to dismiss which took two days.

If the current Senate follows the same format and votes promptly to end the proceeding, the presidential candidates would be forced to stay in Washington through Saturday, Feb. 1, two days before the Iowa caucuses.

But Democrats, including the presidential contenders, continue to argue for the Senate to accept the testimony of new witnesses, a precedent that was followed in 1999. The vote to hear witness testimony that year led to a five-day break to take depositions, another day to prepare and present evidence, and seven more days of trial on the Senate floor.

A repeat of that schedule would not only force the trial to continue through President Trump’s scheduled State of the Union address on Feb. 4, but could disrupt campaigning before the Feb. 11 New Hampshire primary.

Businessman Tom Steyer, the sixth candidate to qualify for the January debate, has only added a couple of days in Iowa to his schedule in recent days. He also has plans for events in North Carolina, South Carolina, New York, California and Nevada before returning to the state in the week before the caucus.

Steyer, who founded a group called Need to Impeach, has spent more time focusing on impeachment than any other candidate in the race, but his staff has expressed worry that the actual proceeding makes it harder for him to deliver his message.

“The coverage is going to be wall-to-wall, so it is going to be harder to get Tom on the national press that we like to have him on,” said Alberto Lammers, the national press secretary for Steyer’s campaign.

Chelsea Janes and Sean Sullivan contributed to this report.