By Gram Slattery and Moira Warburton WASHINGTON (Reuters) -A group of senior New York Republicans on Wednesday called on newly elected U.S. Representative George Santos to resign from office, saying that he had repeatedly lied about his history during his campaign. Even as Republicans in his home district in Nassau County urged Santos to step down, the new congressman rejected their call, telling reporters at the Capitol that he would not resign. The Republicans made the call at a news conference hosted by the Nassau County, New York, Republican party two days after a nonpartisan watchdog accu…