The Democratic primary contenders stuck in Washington for the impeachment trial of President Trump denied frustration with being forced to stay off the campaign trail as the Feb. 3 Iowa caucuses approach.

Sens. Amy Klobuchar of Minnesota, Bernie Sanders of Vermont, and Elizabeth Warren of Massachusetts are expected to spend every day except Sundays on Capitol Hill as jurors during the trial. It’s an unwelcome development for candidates who have pinned their presidential aspirations on a strong finish in the crucial first nominating contest on the Democratic primary calendar.

In interviews Wednesday as they headed to the Senate floor for opening arguments, Klobuchar and Warren did not dispute that being forced off the campaign trail less than two weeks before Iowa could handicap their 2020 prospects. But each described it as their moral duty to adjudicate impeachment articles charging Trump with abuse of power and obstruction of Congress.

“This is my responsibility,” Warren said. “I took an oath of office to uphold the Constitution, and that’s why I’m here. Some things are more important than politics.”

Trial rules require senators to be on the floor for several hours at a time, Monday through Saturday, and prohibit the use of smartphones and other electronics, regulations that limit opportunities to engage with voters on television or via social media. Klobuchar, who has made headway in Iowa, is relying on prominent supporters in the state to stand in for her. The senator conceded she had no other choice.

“I am here doing my constitutional duty; the people of Iowa understand that,” Klobuchar said, noting that she had staffers standing in for her. “Having people on the ground that are people that see folks in the supermarket or at work — that matters.”

Sanders declined to comment. Sen. Michael Bennet of Colorado also is seeking the Democratic nomination but is focused on the Feb. 11 New Hampshire primary and is considered a long shot.

As House Democratic impeachment managers delivered arguments Wednesday, the scene in the Senate resembled a college lecture hall full of students occasionally engaged and interested but often bored and distracted.

Some senators appeared to be taking notes, while others read documents. Some stared motionless at the lectern, listening intently as arguments were made; some did the same while standing. Some stared elsewhere or looked as though they were nodding off. Some made quick conversation with their neighbor to the right or left; some disappeared into the cloakroom for minutes at a time.

Klobuchar and Warren mostly appeared to be reviewing documents or focusing on the House Democrat arguing from the well of the chamber at any given moment. Sanders was more often staring straight ahead, listening to the prosecutor.

Biden leads narrowly in Iowa with 21%, according to the RealClearPolitics average, followed by Sanders with 17.3%, Warren with 16.7%, Buttigieg, the former mayor of South Bend, Indiana, with 16.3%, and Klobuchar with 8.3%.

Sen. Chris Coons, a Delaware Democrat backing Biden, downplayed the fallout his colleagues might experience in the caucuses as a result of the impeachment trial before suggesting the former vice president might profit.

“I don’t think, in the end, that’ll have a huge impact one way. … You’ve got lots of surrogates and advocates for the other candidates who will be out there,” Coons said. “But one of Joe’s greatest strengths is his ability to really connect with people, and time that he has to do town halls and retail campaigning obviously will be to his benefit.”