Rep. Jared Golden's decision to endorse one of House Republicans' most vulnerable incumbents is going down like a lead balloon among his fellow House Democrats.

Why it matters: The anger won't have much impact on Golden (D-Maine), who is retiring, but it could blow back on his closest ally, Rep. Marie Gluesenkamp Perez (D-Wash.).

  • "People are pissed off," a House Democrat speaking on the condition of anonymity to share details of private discussions told Axios, adding, "He is doing Gluesenkamp Perez no favors ... this will hurt her."
  • The Washington Democrat, who often breaks from party leadership and moves as a unit with Golden, "is going to have to figure out how she navigates around the suspicion this will create for her next Congress," this lawmaker said.
  • "He is leaving," said a senior House Democrat. "Marie is a bigger problem."

Driving the news: Golden wrote an op-ed in a local newspaper in Rep. Mike Lawler's New York district endorsing the Republican for reelection.

  • Golden cited his work with Lawler on several pieces of legislation, most notably their bill to exempt lobstermen from certain federal environmental regulations.
  • "Mike Lawler has been a true partner to me and a friend to fishing families he will never represent," Golden wrote. "I strongly back him, and I hope voters send him back to work."

Between the lines: The endorsement comes after Golden and Gluesenkamp Perez, who previously co-chaired the centrist Blue Dog Coalition, repeatedly broke with party leadership on key procedural votes in recent weeks.

  • Twice this month, the two Democrats provided Republican leadership with the votes needed to advance their legislation to the floor, including bills strongly opposed by Democratic leaders.
  • The repeated defections have sparked enormous anger within the House Democratic caucus, with some lawmakers calling to punish Golden and Gluesenkamp Perez.

What they're saying: Democrats met Golden's endorsement with contemptuous dismissal, arguing that it will do little to move the needle for a Republican in a district that went for former Vice President Harris in 2024.

  • House Minority Leader Hakeem Jeffries (D-N.Y.) said in a statement that Lawler is "peddling an 11th hour endorsement from a retiring Congressmember who represents an out of town district more than 400 miles away."
  • "That endorsement should get Mike an additional three votes — comprising most of the New Yorkers who have ever heard of Jared Golden," Rep. Sam Liccardo (D-Calif.) told Axios.
  • A third House Democrat who spoke on the condition of anonymity said similarly: "I don't think it's going to help Lawler. The people in that district who know who Golden is already know who they are voting for."

The intrigue: Just hours after the endorsement, House Democrats' main super PAC announced plans to spend millions more in the media market that encompasses Lawler's district.

  • House Majority PAC said it is reserving $2.45 million more on cable reservations in the New York City media market.
  • Some Democrats have argued against spending large sums to unseat Lawler, arguing that he is one of Republicans' most bipartisan and most politically formidable members.
  • Republicans have been massively outspending Democrats in Lawler's district.