President-elect Donald Trump has chosen Rep. Elise Stefanik to serve as his ambassador to the United Nations.“Elise is an incredibly strong, tough, and smart America First fighter,” Trump said in a statement Monday announcing his pick.Nikki Haley, who challenged Trump for the GOP nomination, was among those who previously held the role in his first term.Stefanik, 40, who serves as House Republican Conference Chair, has long been one of Trump's most loyal allies in the House, and was among those discussed as a potential vice presidential choice.Born and raised in upstate New York, Stefanik graduated from Harvard and worked in former President George W. Bush’s White House on the domestic policy council and in the chief of staff’s office.In 2014, at 30, she became the youngest woman ever elected to Congress, representing upstate New York. She later became the youngest woman to serve in House leadership.Stefanik was known early in her tenure as a more moderate conservative voice. But she soon attached herself to the former president, quietly remaking her image into that of a staunch MAGA ally — and seeing her power ascend.She became the House Republican Conference Chair in 2021.Stefanik spent years positioning herself as one of Trump’s most trusted allies and confidants on the Hill. She endorsed him in the 2024 race before he had even launched his bid, and aggressively campaigned on his behalf during the GOP primary.She saw her profile rise after her aggressive questioning of a trio of university presidents over anti-Semitism on campus led to two of their resignations — a performance Trump repeatedly praised.She also defended him vigorously in both of his impeachment trials and railed against his four criminal indictments, including filing an ethics complaint in New York against the judge who heard his civil fraud case.