At a congressional hearing in December, the congresswoman grilled the presidents of Harvard and the University of Pennsylvania, giving their opponents ammunition and ultimately forcing their resignation.
She asked Claudine Gay, the then Harvard president: “Does calling for the genocide of Jews violate Harvard’s rules on bullying and harassment?”
Dr Gay responded: “It can be, depending on the context.”
In a moment that later went viral, Ms Stefanik shot back: “What’s the context? It’s targeted at Jewish students, Jewish individuals.”
In a statement on Monday, Mr Trump described his appointment as an “incredibly strong, tough, and smart America First fighter”, in a hint at the isolationist stance he expects to take within the UN over the next four years.
Reinvention
Ms Stefanik, a Harvard University graduate, criticised Mr Trump during his first campaign in 2016 but later reinvented herself as one of his closest allies.
She defended him during his 2019 impeachment hearings, earning the status as a “Republican star,” in Mr Trump’s words at the time.
She later adopted some of his toughest talking points, attacking the “Biden Crime Family” over Joe Biden’s son’s business dealings. As House Republican Conference chairman, she is the fourth-most senior GOP representative.
Ms Stefanik has become one of the most prolific Republican media performers, and appeared on stage with Mr Trump during his latest campaign. She was in contention to be his running mate, before JD Vance was appointed the party’s vice-presidential nominee.
“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,” Ms Stefanik said.
“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.”
Her appointment means another Republican will now be appointed to her safely red district in upstate New York, where she was re-elected last week with 63 per cent of the vote.
By law, the state’s governor Kathy Hochul must call a special election within 10 days of the seat’s vacancy, with a vote within three months.