What to Know Six staffers for New Jersey Rep. Jeff Van Drew resigned.

The staffers are resigning after an official announced Van Drew would leave the Democratic party and become a Republican.

Van Drew had also announced he would vote against impeaching President Donald Trump.

Staffers for New Jersey Rep. Jeff Van Drew are resigning over his decision to break from the Democratic party and vote against impeaching President Donald Trump.

Javier Gamboa, Edward Kaczmarski, Justin M. O’Leary, Mackenzie Lucas and Caroline Wood wrote a letter to Van Drew’s Chief of Staff Allison Murphy on Sunday, announcing their resignation.

“We greatly appreciate the opportunities 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. “Sadly, Congressman Van Drew’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.”

Sunday night, NBC News confirmed, Cece Doherty, Van Drew's Director of Constituency Relations, also resigned from his office.

The resignations come a day after a GOP official announced Van Drew, a House freshman, would become a Republican. Top House Republicans were informed of Van Drew’s decision, according to a GOP official familiar with the conversations. The lawmaker had discussed switching parties in a meeting with Trump at the White House on Friday, an administration official said Saturday.

Van Drew's decision underscores the pressures facing moderate Democrats from Trump-leaning districts as next week's impeachment vote approaches. Van Drew won his southern New Jersey district by 8 percentage points last year, but Trump carried it by 5 points in 2016 and Van Drew was considered one of the more vulnerable House Democrats going into next November's congressional elections.

Lawmakers Make One Last Case Before Impeachment Vote

In town halls and main streets across America, representatives about to vote on whether to impeach President Trump are getting one last chance to hear from the people who sent them to Washington.

There are 31 House Democrats who represent districts Trump carried in the 2016 election, and many of them have been nervous about the political repercussions they would face by voting to impeach Trump. The House Republican campaign committee has already run ads targeting many of them, but most are expected to support Trump's impeachment.

A senior Democratic aide said Van Drew had not notified House Democratic leaders about his decision. All the aides spoke on condition of anonymity to describe private conversations.

The senior Democratic aide provided what was described as a poll conducted earlier this month by Van Drew's campaign showing that by more than a 2-1 margin, people in his district would prefer a different candidate than Van Drew in the Democratic primary and general election.

Rumors surfaced last week that Van Drew might switch parties, and he repeatedly denied them to reporters. But he reaffirmed his plan to oppose impeachment, barring new evidence.

"It doesn't mean that I agree with everything the president may have said or done. It means that I don't believe that these are impeachable offenses,” he said in an interview Thursday.

Van Drew and a spokesperson did not answer their cellphones or return text messages on Saturday.

Even with his defection, there remains no doubt that the Democratic-controlled House will vote to impeach Trump on a near party-line vote.

Democrats will still control the chamber by 232-198, plus an independent and four vacancies. Until now, Van Drew and Rep. Collin Peterson of Minnesota were the only Democrats expected to vote against impeachment, with perhaps a small handful of others joining them. House Republicans seem on track to oppose impeachment unanimously.

Van Drew was a longtime state senator. His congressional district had been under Republican control for nearly two decades before he was elected.

The House is set to approve two articles of impeachment against Trump this coming week. In the first article of impeachment, Trump is accused of abusing his presidential power by asking Ukraine to investigate his 2020 rival Joe Biden while holding military aid as leverage. In the second article, he's accused of obstructing Congress by blocking the House's efforts to investigate his actions.

The Republican-controlled Senate is then all but certain to acquit Trump after a trial in January.

Van Drew has argued that the process is likely just to further divide the country and it would be better to let voters decide Trump's fate in next year's election.