For Republican Leaders in Congress, the Headaches Keep Mountingbr That and the uncertain prospects of Senator Dean Heller of Nevada, who is facing a Trump-inspired primary challenger from the right, could endangerbr the Senate majority or at least offset any gains Republicans make in the conservative states where Democrats are facing re-election next year.br Speaking at a high-dollar fund-raiser for his re-election at Le Cirque restaurant in New York last week, Mr. Trump asked contributors what they wouldbr think if he worked with Democrats on health care, should Republicans prove unable to repeal the Affordable Care Act, according to a dinner attendee.br Senator Richard C. Shelby, Republican of Alabama, who was first elected to Congress in 1978, said hebr had never seen rank-and-file Republicans so stirred up against the party’s leaders in Congress.