Through 2019, most House Democrats facing competitive reelection races kept their attention focused on their own brands at home and stayed away from the crowded and hotly contested battle for their party’s presidential nomination.

Recently, however, a few vulnerable lawmakers have started jumping into the fray and backing former Vice President Joe Biden. Some strategists say those decisions could end up helping the endorsers as much as Biden, and more may follow.

Backing Biden early may help these lawmakers fend off Republican attacks tying them to more liberal lawmakers often denounced as “socialists,” such as Vermont Sen. Bernie Sanders and Massachusetts Sen. Elizabeth Warren, and policies such as “Medicare for All,” strategists say.

The endorsements could also signal who is seen by more centrist House members as the most beneficial candidate for the top of the Democratic ticket, with the potential to appeal to independent and Republican-leaning voters who decide elections in competitive districts.

[The 10 most vulnerable House members in 2020: Democrats dominate]

“It may inoculate them a little bit,” said California Rep. Ami Bera, who has endorsed Biden. Bera is a co-chairman of the Democratic Congressional Campaign Committee’s Frontline program for vulnerable incumbents.

“But it also suggests how worried they are about some of these other candidates like Sen. Warren or Sen. Sanders being our nominee,” Bera said. “And the truth of it is, if they’re our nominee, it probably puts our House majority at risk.”

Supporters of Sanders and Warren push back on that claim.

“I don’t think that that’s the case, given the Sanders message, which will mobilize turnout,” said California Rep. Ro Khanna, a co-chairman of Sanders’ campaign. “[Sanders] is very strong in rural communities. And if you look at the states he’s done well in, states like Michigan, states like Wisconsin, those are places where we need to do well.”

Massachusetts Rep. Katherine M. Clark, who was vice chairwoman of recruitment for the House Democrats in 2018 and has endorsed Warren, told CQ Roll Call that Warren’s message would also resonate in competitive House districts. She noted that Warren’s focus on combating corruption, climate change and the high cost of health care were issues discussed in 2018 races.

“These are issues that Elizabeth Warren has fought for her entire professional career and her time as a U.S. senator,” Clark said. “And that is why I think she is going to be a great next president and would be equally helpful to people in all parts of this country.”

One national Democratic strategist cautioned, “I wouldn’t read people endorsing right now as a sign of anxiety.” The strategist said Democrats are focused on aspects of their races that they can control, like fundraising and keeping the focus on local issues.

‘Tip of the iceberg?’

Most Democrats in Congress haven’t endorsed in the presidential primary. But Biden has the highest number of congressional endorsements so far, with 33 House and Senate members supporting him.

Since the start of the year, Biden has picked up endorsements from four lawmakers who flipped House seats in 2018: Abby Finkenauer of Iowa, Conor Lamb and Chrissy Houlahan of Pennsylvania, and Elaine Luria of Virginia. Finkenauer, Lamb and Luria represent districts President Donald Trump won in 2016, and all three are in the DCCC’s Frontline program. 

Bera said the recent endorsements were “the tip of the iceberg,” and he expects more of the 44 Democrats in the Frontline program to back Biden. Bera pointed to Biden’s prevalence on the 2018 campaign trail as proof that he can help Democratic candidates in competitive races.

For the 2018 election, Biden traveled to 24 states to campaign for 65 candidates, a stat he touted at an event with Finkenauer this week. Biden held campaign events for 22 House candidates, according to media reports and the Biden campaign. The majority of those candidates were running in districts Trump won in 2016, and all but two of them won their races two years later.

Of the 20 House Democrats who held events with Biden and are now in Congress, just four — Luria, Finkenauer, Lamb and Pennsylvania Rep. Matt Cartwright — have endorsed the former vice president. The New York Times reported Wednesday that California Rep. Harley Rouda, who was at a rally with Biden one month before the 2018 election, will host a fundraiser for Biden. Rouda’s campaign manager, Alyssa Napuri, said in an email to CQ Roll Call that Rouda was not endorsing in the primary “at this time.”

Some of the candidates who appeared with Biden in 2018 have endorsed someone else for president. New Jersey Reps. Andy Kim and Mikie Sherrill both backed their home-state senator, Cory Booker, who also campaigned often with them in 2018. California Rep. Katie Porter, who appeared at the same Orange County rally with Biden as Rouda, has endorsed Warren, her former professor and mentor. Florida Rep. Stephanie Murphy endorsed former Texas Rep. Beto O’Rourke, who has since dropped out.

“This was a crowded field,” Bera said when asked why some Democrats who brought Biden to their districts have not yet endorsed him. “I think folks are now starting to tune in and think about the other races that are ahead of them.”