Former Obama White House Chief of Staff Bill Daley lambasted Sen. Heidi HeitkampMary (Heidi) Kathryn HeitkampSenate rejects Trump immigration plan Cramer to announce North Dakota Senate run on Friday Senate Democrats not sold on bipartisan immigration deal MORE (D-N.D.) and other Democrats who voted this week against an amendment to bolster background checks for firearms, warning that gun control advocates would not forget.

In a scathing opinion piece penned for The Washington Post, Daley recounted contributing $2,500 to Heitkamp’s successful 2012 bid to become North Dakota’s junior senator.

Now, Daley said, “I want my money back.” 

“She struck me as strong-willed, principled and an independent thinker,” Daley wrote. “But this week, Heitkamp betrayed those hopes. “

Daley’s ire centers on Wednesday’s vote on a bipartisan amendment to strengthen background checks on gun purchases. Proponents of the measure fell half a dozen votes shy of the 60 needed for passage in a major blow to efforts to tackle gun control through legislative action.

Heitkamp defended her vote.

“Throughout the debate, I stood firm and protected the Second Amendment rights of North Dakotans,” she said in a written statement after the amendment was defeated.

Citing her background as an attorney general, Heitkamp said focusing on mental health issues and shoring up the National Instant Criminal Background System (NICS) would be a better approach than the proposal crafted by Sens. Joe ManchinJoseph (Joe) ManchinPavlich: The claim Trump let the mentally ill get guns is a lie Toomey to introduce bill broadening background checks for firearms Scott Walker backs West Virginia attorney general in GOP Senate primary MORE (D-W.Va.) and Pat Toomey (R-Pa.).

“I felt the Manchin-Toomey amendment ultimately would place undue burdens on law-abiding North Dakotans,” Heitkamp said.

But Daley pointed to polling suggesting that 94 percent of the state’s residents supported the amendment and said it was “more likely that she heard from the gun lobby and chose to listen to it instead.”

Daley also had harsh words for Sens. Mark PryorMark Lunsford PryorMedicaid rollback looms for GOP senators in 2020 Cotton pitches anti-Democrat message to SC delegation Ex-Sen. Kay Hagan joins lobby firm MORE (D-Ark.) and Max BaucusMax Sieben Baucus2020 Dems pose a big dilemma for Schumer Steady American leadership is key to success with China and Korea Orrin Hatch, ‘a tough old bird,’ got a lot done in the Senate MORE (D-Mont.), who also voted against the measure. Both are up for reelection next year.

“And no doubt they’ll come to Chicago, New York, Los Angeles and other cities looking for money to fuel their campaigns,” Daley wrote.  “So I’ll have some advice for my friends in Chicago, New York and Los Angeles: Just say no to the Democrats who said no on background checks.”

This story was updated on Sunday at 2:56 p.m. to correct the the amount that Daley contributed This story was updated on Sunday at 2:56 p.m. to correct the the amount that Daley contributed