WASHINGTON, March 2 (Reuters) - The U.S. House of Representatives Ethics Committee said on Thursday it had opened an investigation into Republican congressman George Santos, who has admitted to lying about his resume but defied calls to step down. The first-term lawmaker from New York state has admitted he fabricated much of his resume. Santos had said he had degrees from New York University and Baruch College, despite neither institution having any record of him attending. Santos has refused to step down despite mounting pressure from within his own party, insisting that he is the elected representative for New York's third district. Republicans control an extremely narrow margin in the House, in part thanks to surprise victories in New York state like Santos, who flipped his district in November's midterm elections.

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