WASHINGTON — Rep. Jeff Van Drew, the conservative South Jersey Democrat who has vocally opposed impeaching President Donald Trump, is expected to switch parties in the coming days, according to three New Jersey Democratic sources, leaving a party he has represented for more than 20 years.

Van Drew didn’t just oppose the impeachment effort. He repeatedly touted his position on Fox News, winning direct praise from Trump on Twitter. “Thank you,” the president wrote in one tweet in September.

In turn, Democrats saw his support implode in polling and party leaders began distancing themselves from the congressman. This week the Democratic chairman of Atlantic County warned in a public letter that Van Drew would infuriate Democratic voters and could cost the party down ballot next year if he opposed impeachment. State Senate President Steve Sweeney (D., Gloucester), a longtime Van Drew ally, pointedly refused to endorse the congressman.

"Jeff stabbed us in the back, certainly,” said a seething Michael Suleiman, the Atlantic County chairman. "It’s disgusting. It’s a disgrace. Good riddance.”

He added, “Maybe he’ll be the new ambassador to Ukraine.”

With activists furious about Van Drew’s stand, one New Jersey Democrat said that there was no way the congressman from Cape May County could win a primary and that party leaders would not have backed his reelection in 2020.

The sources spoke on the condition of anonymity to disclose private discussions. Van Drew and his chief of staff did not respond to messages seeking comment.

Gov. Phil Murphy said in a statement Saturday that he and other top Democrats had made it clear to Van Drew that his impeachment stand meant he would no longer have Democratic support. “Despite knowing full well that the president has abused the powers of his office,” Murphy said, “Congressman Van Drew is now willing to enable Donald Trump just to try to salvage his own election.”

Van Drew in recent days asked party chairs to sign a pledge to support him, and they refused, according to Sulemain. Van Drew’s team also tried to persuade national Democratic staffers detailed to his race to continue to support him despite his switch to the GOP. The Democratic Congressional Campaign Committee staff balked and alerted South Jersey Democratic officials, according to two people familiar with the conversations.

Suleiman had supported Van Drew in a crowded primary in 2018 over objections from progressives, and over concerns about Van Drew’s positions on guns and other issues.

“People held their nose because they wanted to keep the seat blue,” Suleiman said. “We said, ‘He’s going to be with us on the big issues, and we need to get that seat back.’ He did have some good Democratic positions.”

Indeed, Van Drew voted with Trump only about 7% of the time, according to FiveThirtyEight, a data-focused news site. But the impeachment vote was a breaking point. Van Drew was one of two House Democrats to break ranks on opening the inquiry, and he has said he plans to vote against formal articles of impeachment against Trump next week.

His defense of Trump often echoed Republican talking points, including by raising questions about Joe Biden’s conduct. Republicans in Washington pointed to Van Drew’s vote against an impeachment inquiry as a sign of bipartisan opposition to the effort.

“The Democrats’ impeachment sham is so unpopular that even their own members are fleeing the party,” the Republican National Committee said Saturday.

Some in South Jersey argued that Van Drew’s October vote against opening the inquiry cost Democrats state legislative seats days later. His allies ran under the banner of “the Van Drew team,” a brand that became toxic among Democratic voters. A recent Democratic poll in Van Drew’s district, obtained by The Inquirer, found that only 24% of likely Democratic voters thought Van Drew deserved to be reelected, while 60% wanted someone new.

>>READ MORE: New Jersey’s Jeff Van Drew is becoming Trump’s favorite Democrat

Van Drew’s sprawling South Jersey district has long been a political battleground. It twice supported Barack Obama but repeatedly reelected Republican Rep. Frank LoBiondo. It flipped to Trump in 2016, but Van Drew won it for Democrats last year. The race for the seat was already expected to be one of the toughest in the country, and could be even more charged now.

“New Jersey politics,” LoBiondo tweeted Saturday, “never boring.”

Van Drew, 66, had long won campaigns in a relatively conservative area by walking a fine line, breaking with his party on some top priorities, such as tougher gun laws.

>>READ MORE: Inside the ‘very awkward’ South Jersey congressional race between former friends Jeff Van Drew and Seth Grossman

It wasn’t immediately clear whether Van Drew would win GOP support. If the president endorses Van Drew, that would be a significant boon with party leaders, but Republican activists have a long history battling the congressman during his two decades in the state Assembly and Senate. Some longtime rivals on Saturday were already pointing to his frequent votes for the agenda pushed by House Speaker Nancy Pelosi.

Several other Republicans are already running. “It’s not a coronation,” said Keith Davis, the Republican chairman in Atlantic County. “We’ll see.”

On the Democratic side, Brigid Harrison, a Montclair State University professor and political analyst, was the early name being considered by South Jersey Democrats. Harrison said Saturday an announcement of her candidacy was “imminent.”

She had already been mulling a run against Van Drew in a primary. Reached at the Army-Navy game in Philadelphia, Harrison called Van Drew a “traitor to his party.”

She said she had spoken with the many county chairs in the district, and “they have all been quite positive and favorable.”

“He was choosing his own political career over the Constitution and the future of the country,” Harrison said.

South Jersey Democrats did not feel any particularly loyalty to Van Drew. They supported him in 2018 because he’d helped make Sweeney the Senate president. Once he was in Congress, Van Drew was no longer seen as particularly useful to the area’s powerful Democratic machine.

Said one Democrat, “He got the boot.”

Sue Altman, state director for New Jersey Working Families, blasted Van Drew, as well as national and state Democratic leaders, and the South Jersey machine for supporting him in the first place.

“Everyone in New Jersey politics was fully aware Van Drew has, for decades, been a Republican disguised as a Democrat,” Altman said in a statement.

Staff writer Pranshu Verma contributed to this report.