Rep. Peter King — the 14-term Republican leader of New York’s congressional delegation who was an outspoken advocate for 9/11 compensation and Hurricane Sandy reconstruction — said Monday that he won’t seek re-election in 2020.

King’s decision makes him the 20th GOP lawmaker to opt against seeking re-election since the election of President Trump and sets the stage for a likely highly competitive contest to represent the 2nd District next fall.

“The prime reason for my decision was that after 28 years of spending four days a week in Washington, DC, it is time to end the weekly commute and be home in Seaford,” the 75-year-old King said in a statement.

The seasoned GOP lawmaker confessed that punting on a possible 15th term “was not an easy decision,” but cited a desire to spend more time with his wife and their two children.

“My time in Congress has been an extraordinary experience,” he added.

Since George H.W. Bush sat in the Oval Office, King has represented Nassau and Suffolk counties on Capitol Hill, where he’s made his name as a limelight-loving open book.

“I hate Ted Cruz,” he bluntly snapped when asked by MSNBC in 2016 about the Texas Republican’s presidential prospects. “I think I’ll take cyanide if he ever got the nomination.”

But King’s shoot-from-the-hip persona was in the service of the causes he championed.

Despite traditional conservative views on immigration, criminal justice and national security, King — a member of the House Financial Services Committee and the Committee on Homeland Security, which he formerly chaired — demonstrated a repeated willingness to work with Democrats.

King became the first Republican to join 200 Democrats in a failed push for an assault-weapons ban — championed by The Post — in the aftermath of massacres in Texas and Ohio that horrified the nation. And he regularly took GOP leaders to task for dragging their feet in aiding 9/11 heroes and survivors of Hurricane Sandy.

The lawmaker also worked closely with President Bill Clinton in hammering out the Good Friday Agreement, a major step toward peace in Northern Ireland.

“Peter King stood head & shoulders above everyone else,” tweeted Democratic New York Sen. Chuck Schumer. “He’s fiercely loved America, Long Island, and his Irish heritage and left a lasting mark on all 3.”

Even before King announced his retirement, Democrats were already strategizing on how to flip his district, which went for Trump in 2016 but backed Democrats in the five prior presidential elections.

Babylon Councilwoman Jackie Gordon has thrown her hat in the ring and Liuba Grechen Shirley — who came within 6 percentage points of unseating King in 2018 — said she is mulling another run.

King’s fellow Republicans were also eyeing the emptying seat.

State Assemblyman Michael LiPetri acknowledged that he was considering a run after hearing an “outpouring of support” from his Long Island constituents.

And former Rep. Rick Lazio told the National Journal, “I will be thinking through what that means for the district — beyond the obvious.” He played coy when asked by The Post, saying he would “leave other considerations to another day.”

With Wires