President-elect Donald Trump has named Republican Congresswoman Elise Stefanik to serve as the US ambassador to the United Nations.

A longtime Trump ally, Stefanik is a staunch supporter of Israel and has also been critical of the UN for what she argues is a lack of sufficient backing for its war against Hamas.

“Elise is an incredibly strong, tough, and smart America First fighter,” Trump said in a statement confirming the first cabinet pick of his second term.

If confirmed, Stefanik would replace UN Ambassador Linda Thomas-Greenfield, a career diplomat who worked for the US Foreign Service for 35 years.

Stefanik said she was "deeply humbled" to accept Trump's nomination and was looking forward to "earning the support of my colleagues in the United States Senate", which must vote on her nomination to make it official.

“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 added in a statement given to the New York Post.

The New York Congresswoman has minimal experience in foreign policy and national security. She has served on the House Armed Services Committee and the House Permanent Select Committee on Intelligence.

Since Hamas's 7 October attack, she has become one of the most outspoken supporters of Israel in Congress, garnering national attention as she led congressional hearings about university presidents' handling of protests on college campuses.

Last month, she argued there should be a “complete reassessment of US funding of the United Nations” after the Palestinian Authority tried to expel Israel from the UN over human rights abuses in Gaza.

In a statement on Monday, Israel's international spokesperson to the UN said the country's ambassador, Danny Danon, "looks forward to working closely with Elise Stefanik on tackling malicious lies at the UN advanced by hostile nations while staying unswervingly committed to truth and justice".

Before Trump's announcement, Stefanik had risen to become the highest ranking woman in House Republican leadership.

Born and raised in upstate New York, the congresswoman was the first member of her family to earn a college degree after graduating from Harvard University in 2006.

Soon after, she entered politics, serving as a White House domestic policy adviser under President George W Bush and eventually becoming a senior aide to Bush chief of staff Joshua Bolten.

Stefanik later became a top campaign adviser for Paul Ryan when he ran for vice-president alongside Mitt Romney. When Romney lost, the then-30-year-old moved back to upstate New York and ran for Congress, flipping a Democratic-controlled seat with a win by over 20 points.

Stefanik once billed herself to voters as a traditional conservative, but emerged as one of Trump's most ardent defenders during the first impeachment trial against him in 2019. Her support for Trump has not wavered since.

“I’m proud to be a top surrogate,” Stefanik said earlier this year of her support for the president-elect. “I would proudly serve in a future Trump administration.”

Her appointment would leave open the 21st Congressional District seat in New York, which would lead to a special election.

Some Trump allies, including billionaire Elon Musk, have argued it is too risky to lose Stefanik's seat as Republicans and Democrats battle for control of the House, which remains too close to call.