WASHINGTON — New York Rep. Elise Stefanik has accepted President-elect Donald Trump’s offer to be his enforcer as United Nations ambassador, The Post can reveal.

The 40-year-old upstate Republican, who helped force out two Ivy League presidents with her sharp questioning on campus antisemitism, will the lead Trump’s “America first” and pro-Israel message in Turtle Bay.

“I am honored to nominate Chairwoman Elise Stefanik to serve in my Cabinet as U.S. Ambassador to the United Nations. Elise is an incredibly strong, tough, and smart America First fighter,” Trump, 78, said in a statement to The Post Sunday night.

Stefanik, the No. 4 House Republican, has been a close Trump ally, including serving on his ceremonial defense team in 2020 during his first impeachment trial for pressuring Ukraine to investigate alleged Biden family corruption.

The Harvard grad worked to turn the tables on what she called the “Biden Crime Family” and has regularly appeared on TV to drive home the Republican positions on issues — setting up a likely a contrast from the outgoing UN ambassador Linda Thomas-Greenfield, who rarely courted media attention.

“I am truly honored to earn President Trump’s nomination to serve in his Cabinet as U.S. Ambassador to the United Nations,” Stefanik said in a statement confirming her acceptance of the role.

“During my conversation with President Trump, I shared how deeply humbled I am to accept his nomination and that I look forward to earning the support of my colleagues in the United States Senate.”

“President Trump’s historic landslide election has given hope to the American people and is a reminder that brighter days are ahead — both at home and abroad,” she told The Post.

“America continues to be the beacon of the world, but we expect and must demand that our friends and allies be strong partners in the peace we seek.”

Stefanik will come on as the UN has faced conservative criticism, including over the fact that the world’s dictatorships — such as China and Cuba — serve as reps on the Human Rights Council, while the General Assembly routinely passes measures critical of Israel by lopsided margins.

More recently, the UN has come under fire for its response to the Israel-Hamas war and has faced accusations that members of its organizations actively took part in Hamas attacks against Israel.

In his first term, Trump ordered the US to withdraw from the UN’s World Health Organization and end the annual $450 million US contribution over the WHO failing to effectively investigate the origins in China of the COVID-19 pandemic.

Retiring President Biden later rejoined.

The nomination was one of the first major staffing decisions from Trump after he completed a stunning political comeback with his Tuesday election sweep of swing states against Vice President Kamala Harris.

Trump previously announced his campaign chairwoman Susie Wiles as his White House chief of staff, but he has not yet announced any other members of his Cabinet or other senior White House roles.

“The work ahead is immense as we see antisemitism skyrocketing coupled with four years of catastrophically weak U.S. leadership that significantly weakened our national security and diminished our standing in the eyes of both allies and adversaries,” Stefanik said in her statement.

“I stand ready to advance President Donald J. Trump’s restoration of America First peace through strength leadership on the world stage on Day One at the United Nations. “

Stefanik’s departure from the House would temporarily reduce Republicans’ already slim majority.

Gov. Kathy Hochul (D-NY) by law must call a special election within 10 days of the seat’s vacancy to be held within another 70-80 days. The Republican nominee in that election will be chosen by county GOP chairs rather than by a primary.

Stefanik was re-elected Tuesday with more than 63% of the vote.

A source familiar with the looming special election campaign called the district “ruby red” and solidly “pro-Trump,” adding that “the seat will not remain vacant for long.”