Billy Joel’s ex-girlfriend Trish Bergin Weichbrodt is going to start the fire — by running for Congress.

Republican Bergin Weichbrodt, a Town of Islip councilwoman, will throw her hat in the ring to replace Rep. Peter King, who announced his retirement on Monday.

Bergin, 48, a former TV news reporter, told The Post that she will submit paperwork with the Federal Elections Commission on Thursday to declare her candidacy for the second congressional district, which includes parts of Suffolk and Nassau counties.

“Yes, I’ve submitted my papers to begin ‘Trish Bergin for Congress,'” she said.

“I’m excited to be considered to represent the residents of Long Island in Washington and on the forefront of the issues that affect us globally.”

One GOP leader said Bergin will be a formidable candidate because, well, “She’s Just Got A Way About Her.”

“Trish has experience as a legislator. She’s media savvy. She’s bold. She’s independent,” said former Suffolk County Republican leader John Lavalle.

Her former ties to Joel, who is revered on Long Island, is generating chuckles.

“This race wasn’t Long Island enough? So, of course, we needed a @billjoel angle to it somehow,” tweeted Jason Elan, spokesman for Democratic Suffolk County Executive Steve Bellone.

The GOP has treated Bergin as a rising star. She was one of three finalists considered to run as the party’s candidate for lieutenant governor last year.

But she also caused a storm and apologized last year after she poked fun on Facebook at countries President Trump allegedly derided as “sh–holes.”

“I’m looking at warm getaways for kids February break. I’m wondering about El Salvador, Haiti or Somalia #recommendations?,” she said.

She deleted the post amid a backlash and apologized.

Joel is said to still be a fan of Bergin, who broke the Piano Man’s heart when she nixed his marriage proposal in 2000.

Joel told Page Six back in 2009 that he’d back Bergin when she first mulled a run for county legislator.

“I would vote for Trish Bergin in a heartbeat,” Joel said.

“She’s always had the best interests of Long Island in mind, and she was always very well-informed about our important local issues.”

Other GOP candidates considering the race include former Rep. Rick Lazio and Suffolk Board of Elections Commissioner and Navy veteran Nick La Lota.