At least half a dozen congressional staffers have resigned from freshman Rep. Jeff Van Drew’s office, ABC News has learned, after they said the moderate New Jersey Democrat informed them of his plans to join the Republican Party.
The questions over Van Drew's party allegiance were reported by several news outlets over the weekend, ahead of the House vote on articles of impeachment against President Donald Trump.
The congressman's office did not respond to a request for comment on whether Van Drew is officially switching parties.
Van Drew, whose district leans Republican and was carried by Trump in 2016, told reporters that he plans to oppose both articles of impeachment.
(MORE: Democrats call for Mulvaney, Bolton to testify in Senate's Trump impeachment trial)In a letter to Allison Murphy, Van Drew’s chief of staff, five staffers on Sunday said the congressman’s decision to "join the ranks of the Republican Party led by Donald Trump does not align with the values we brought to this job when we joined his office."
"We greatly appreciate the opportunity that the Congressman has given us, and we are proud of the work we’ve done together on behalf of the people of New Jersey’s Second Congressional District," they wrote.
The staffers, who said they were "deeply saddened and disappointed" by "Van Drew’s decision", include legislative director Javier Gamboa, deputy chief of staff Edward Kaczmarski, deputy chief of staff and scheduler Justin O’Leary, communications director Mackenzie Lucas and legislative assistant Caroline Wood.
CeCe Doherty, director of constituent services, also resigned Sunday night, Doherty confirmed to ABC News.
According to a person close to the situation, a staff assistant who wanted to remain anonymous also resigned Sunday night.
"Defeating Trump has and always will be the main goal for me. It’s the reason I got involved in politics. I could not, in good conscience, continue working in an office where mutual morals and values were no longer present," Doherty said in a statement.
Murphy did not respond to messages seeking comment. Van Drew has not as of Monday afternoon formally informed House Democratic leadership of his decision to switch parties, according to a House Democratic leadership aide.
Rep. Cheri Bustos, chairwoman of the Democratic Congressional Campaign Committee, House Democrats’ campaign arm, offered jobs to the resigning aides via tweet Sunday.
"It's right before the holidays and these staffers just quit their jobs to stand up for their Democratic values. We'll bring them and others who leave on with the @dccc until they land new jobs that align with their values," Bustos wrote.
A DCCC spokesperson told ABC News that Van Drew staffers who resign "will be offered paid full-time employment while we help them find future employment."
The move comes after the DCCC commissioned a poll, which a senior Democratic source shared with ABC News, that showed a majority of Van Drew's constituents think someone new should be re-elected in 2020.
(MORE: Dems only care about partisan attacks: Sen. Ted Cruz)New Jersey Gov. Phil Murphy, a Democrat, blasted Van Drew in a statement Saturday, saying the congressman has "chosen his political career over our Constitution."
As recently as last week, Van Drew’s office was seeking contributions and campaign funds from other House Democrats, touting his vulnerable status as a vulnerable House Democrat, a Democratic source familiar with the request told ABC News.
On Sunday, Trump, who has previously tweeted about Van Drew’s opposition to impeachment, reacted to reports of Van Drew’s planned switch.
"Wow, that would be big. Always heard Jeff is very smart!" the president said on Twitter, retweeting a story reporting that Trump met with the congressman Friday and urged him to switch parties.
Van Drew, one of two Democrats to vote against the resolution launching the impeachment inquiry, said on Thursday that he still plans to oppose impeaching the president when it comes time to vote this week, but doesn’t expect many Democrats to join him.
The congressman told reporters Thursday that he's hearing from constituents on both sides of the impeachment debate, and the breakdown of calls to his office is about 50/50 on the issue.
"Whatever you do, you are going to aggravate people," he said, adding that he had seen "no" new evidence or testimony that could convince him to vote for impeachment.
The congressman flipped his district from red to blue, winning the election by a nearly 8-point margin. The district went for Trump over his 2016 challenger, Hillary Clinton, by a margin of 4.6 percentage points.
The primary campaign to fill Van Drew's seat is already gearing up. On Monday, Brigid Harrison, a political science professor at Montclair State University, announced she's running as a Democrat.