WASHINGTON — Less than a month before the Iowa caucuses, Democratic presidential candidates should be finalizing plans for campaign blitzes in the state with the nation's first nominating contest.

Instead, five 2020 contenders are wondering how often they'll be able to set foot there at all, with senators preparing to sit as jurors in President Donald Trump's impeachment trial, which is expected to begin sometime this month.

The Senate has not yet set rules or a schedule for the trial, but many senators, including some of those running for the Democratic presidential nomination, believe it will look something like Bill Clinton's impeachment trial in 1999. Senators met for the trial every afternoon, six days a week, Monday through Saturday, from Jan. 7 to Feb. 12.

A Trump trial lasting that long has the potential to disrupt campaigning in both Iowa (which votes Feb. 3) and New Hampshire (which votes Feb. 11).

Of the five senator-candidates — Elizabeth Warren of Massachusetts, Bernie Sanders of Vermont, Cory Booker of New Jersey, Amy Klobuchar of Minnesota and Michael Bennet of Colorado — Sanders appears to be the best positioned to balance his senatorial duties with campaigning.

Sanders' war chest, including his field-leading $34.5 million haul in the last quarter of 2019, allows him flexibility that other contenders can't match — including the use of private jets to ferry him back and forth for late rallies in early states.

"They're not going to be meeting at night [for the trial], so we can obviously fly from D.C. to states and hold events in the evening and fly back, you know, so he can be back in the morning to do his work in the Senate," Sanders campaign adviser Jeff Weaver told NBC News.

"He's an energetic candidate," Weaver added. "He has a very vigorous schedule, and, you know, he can do that."

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Sanders can also call upon a network of surrogates and endorsers with track records of drawing big crowds among progressives, most notably three members of "the Squad" — Reps. Alexandria Ocasio-Cortez of New York, Rashida Tlaib of Michigan and Ilhan Omar of Minnesota — who are now freed from their own impeachment duties in the House.

The other top Senate candidate, Warren, has been coy about her campaign plans during a trial, but she shares similar advantages to Sanders, although on a smaller scale, with healthy fundraising and several potentially high-value surrogates like Reps. Ayanna Presley and Joseph Kennedy of Massachusetts. After dropping out of the race last week, Julian Castro endorsed Warren on Monday, giving her a strong surrogate who is already well known in the state and who could campaign for her during the trial.

Candidates with less money in the bank and shorter benches of those who can campaign in their stead may find the trial more stifling.

Booker and Klobuchar have said they will campaign from Washington in early voting states by video-conferencing and Skype and will send surrogates of their own on the trail. Both have recently begun airing television ads and may depend on them to keep a presence in early states during the trial.

"When I get to be in a room and connect directly with people, we pull them over to support our campaign," Booker said last week. "Not to be able to do that for a week or two weeks is going to be difficult."

Travel logistics will also have an outsize effect on campaign strategy. A campaign aide to Bennet said his longstanding focus on New Hampshire — easily reachable by a flight of under 500 miles from Washington — gives him something of an edge over candidates more committed to competing in Iowa, which is 1,000 miles from the capital.

Candidates who are not senators will find the early states less crowded during the week, a possible advantage in a tight race. But they also face a different set of challenges during a trial: how to persuade voters to focus on the campaign with the Trump trial likely to dominate national news coverage.

"I think we're going to have to learn to talk about many important things at the same time, as you do in any presidential campaign process," former South Bend, Indiana, Mayor Pete Buttigieg told reporters last week.

"It'll reach a new level with impeachment going on," he added, "but I also think that the American people are capable of following these conversations about the policies that will affect their lives and the process for holding the president accountable."

Former Vice President Joe Biden's advisers have argued that an impeachment trial might bolster their candidate's case, given the degree to which Biden has focused on attacking Trump's fitness for office.

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For his part, Andrew Yang has argued that senators should feel free to continue to campaign on the ground during the trial, given the slim odds of a conviction in the Republican-controlled Senate.

"I do think that the American people are more interested in a positive vision that we can all get excited about rather than impeachment proceedings, particularly as approximately zero Republicans have signaled any interest in even contemplating successful impeachment of the president," Yang told reporters.

"Any of the senators in the field should also be free to make the case, and they should not be constrained by the timeline of the Senate trial," he added.

With the start date of the trial still unsettled, no senator has appeared interested so far in taking up Yang's offer.

"There are some things that are more important than politics," Warren told reporters last month. "I took an oath of office to uphold the Constitution, and if we have an impeachment trial in January, I will be there."