Five aides to Rep. Jeff Van Drew, the freshman Democratic congressman who reportedly plans to vote against impeachment and switch to the Republican Party, resigned on Sunday, CNN reported.

Among those who quit were the congressman’s legislative director, communications director and his scheduler.

The staffers wrote in a letter that they can "no longer in good conscience continue our service in the Congressman's employ," adding that his decision to join the ranks of the Republican Party led by (President) Donald Trump does not align with the values we brought to this job when we joined his office."

Democratic sources told CNN that Van Drew was not doing well in polls among Democrats in his district and that by switching parties he can avoid a Democratic primary challenge.

In October Van Drew voted against formalizing the impeachment inquiry, one of just two Democrats to do so. He said earlier this month that he would also oppose all articles of impeachment.

Van Drew flipped his GOP district in last year’s midterms as Democrats captured the majority in the House, according to Politico. However, the district voted for Trump in 2016 and continues to lean Republican.