WASHINGTON/NEW YORK - For the Republican Party, a tough job just got a little tougher thanks to Donald Trump.For years, Republicans, backed by some influential donors, have carefully cultivated the vote of Jewish-Americans who regard the security of Israel their top concern. Less than a week ago, a bevy of presidential candidates stood before a group of Jewish conservatives in Washington, asking for their support and declaring their solidarity with the Jewish state.But Trump's proposal to bar the entry of all foreign Muslims into the United States has upended some of those efforts, prominent Republicans said. His planned visit to Israel at the end of December is being viewed with increasing concern."It's unquestionably unhelpful. His comments are disgusting," Norm Coleman, a former senator from Minnesota and a board member of the Republican Jewish Coalition, told Reuters."The Jewish community, collectively, has that institutional memory, and institutional scars from previous events in history where a group based solely on religion was persecuted," said Lee Cowen, a Republican strategist, adding that Trump was damaging the party."They are very weary of somebody repeating the same kind of rhetoric but just changing the name of the religion."