House Judiciary Committee Chairman Jerrold Nadler, D-N.Y., said Sunday the only reason anti-impeachment Rep. Jeff Van Drew, D-N.J., is set to switch parties is because he saw polling that suggested Democrats in his district don't want to renominate him.

"What he's reacting to is public polling that shows he can't get renominated," Nadler told ABC's "This Week." "His electorate in his district is 24 percent to renominate him and 60 percent to nominate somebody else."

"But more to that point, this is not political," Nadler said of impeachment. "We should not be looking at those things. This is the defense of our democracy. Do we stay a democratic republic or do we turn into a tyranny?"

Two Democratic leadership sources told NBC News Saturday that Van Drew, who resides in a southern New Jersey swing district and is an outspoken opponent of impeachment — is likely to soon switch parties and become a Republican.

Trump excitedly welcomed the news, tweeting, "Wow, that would be big" after earlier thanking Van Drew for his "honesty" in speaking out against impeachment.

An internal poll conducted for Van Drew this month and obtained by NBC News suggested the congressman was unlikely to make it through a Democratic primary in New Jersey's 2nd Congressional District, with just 28 percent of Democratic respondents saying Van Drew "deserves to be re-nominated," while 58 percent said that "another Democrat" should be the party's nominee in 2020.

"The leading Democrat opposed to impeachment is switching parties to protect Trump," former Vice President Joe Biden tweeted Sunday, soliciting donations for the eventual Democratic nominee in that district. "The best way to beat him is to give him a well-funded opponent — and a strong campaign at the top of the ticket."

In 2018, Van Drew won his seat with 52.9 percent of the vote. His district voted for Trump in 2016 after supporting Barack Obama in 2008 and 2012.

"Despite knowing full well that the president has abused the powers of his office, Congressman Van Drew is now willing to enable Donald Trump just to try to salvage his own election," New Jersey Gov. Phil Murphy, a Democrat, said Saturday in a statement.

The House Judiciary Committee approved two articles of impeachment against Trump on Friday for his efforts to have Ukraine probe Biden, his son Hunter Biden and Democrats, and his efforts to withhold information from Congress as they probed his conduct. The articles are expected to be passed in a Wednesday before the full House vote. Trump would then be tried in the Senate.