Elise Stefanik (R-N.Y.) to serve as U.S. ambassador to the United Nations on Monday, further elevating her seismic rise in the Republican Party. It is a major nod to the chair of the House Republican Conference — and the highest-ranking GOP woman in the lower chamber — who has been one of Trump’s fiercest defenders and supporters in recent years.

Donald Trump will nominate New York congresswoman Elise Stefanik to join his administration as U.S. ambassador to the United Nations, the president-elect told the New York Post on Sunday. “Elise is an incredibly strong, tough, and smart America First fighter,” Trump said in a statement to the newspaper announcing his decision.