Washington — New Jersey Senator and Democratic presidential candidate Cory Booker said President Trump's upcoming impeachment trial and other issues demanding his attention in Washington could be a "big, big blow" to his efforts to win next month's Iowa caucuses.

Booker told The Associated Press in an interview for its "Ground Game" podcast that his campaign's internal metrics indicate he would finish in a "pretty exciting place" in the February 3 caucuses, but his Senate responsibilities could hamper his ability to remain competitive.

"It's going to be a challenging four weeks into caucus for us where our strengths are going to be under assault, so to speak, from all the things going on in our country right now," he said. "Our weaknesses are going to be seen because, again, if we can't raise more money in this final stretch, we won't be able do the things that other campaigns with more money can do to really show presence."

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Booker said his campaign is under "major pressure" to bring in donations, which would allow him to remain on the airwaves in the coming weeks if he cannot be in Iowa.

"We have real demanding things going on in Washington," he said. "I swore an oath to do this job and I'm going to do it."

Booker is one of five Democratic senators running for president who could be forced to spend the days leading up to the Iowa caucuses participating in the impeachment trial in the Senate. The parameters of the proceedings, however, have not yet been agreed to, including how long they will last and whether witnesses will be called.

The House voted last month to impeach Mr. Trump, but House Speaker Nancy Pelosi has refused to send the two articles of impeachment to the Senate until Republicans publish a resolution outlining the rules for the trial. The upper chamber cannot begin a trial without the articles, and Senate Majority Leader Mitch McConnell has said Republicans have the votes to approve a resolution without negotiating with Democrats.

Booker said a Senate lasting just two weeks would force him to cancel "literally dozens" of events where he could drum up support from caucus-goers.

In addition to the impeachment trial, escalating tensions between the U.S. and Iran will require Booker's attention.

The New Jersey senator returned to Washington for an all-Senate briefing Wednesday on the Trump administration's targeted strike that killed top Iranian military commander Qassem Soleimani last week. Lawmakers have raised questions about the justification for the attack ordered by Mr. Trump, and congressional Democrats are preparing to vote on a measure to limit his war-making powers.

Booker said he is confident his campaign will exceed expectations in Iowa, which would give him momentum heading into contests in states with more diverse electorates. Still, he has not qualified for next week's Democratic presidential debate in Des Moines, the final debate before the caucuses.

Booker has also not been shy about his fundraising struggles. In September, Booker's campaign manager warned he needed to bring in at least $1.7 million by the end of the third quarter in order to stay in the race. Booker also urged voters last month to donate to his campaign, telling "Face the Nation" in an interview he needed their help.