WASINGTON — Republicans sympathize with Israel in its conflict with Palestinians increasingly more strongly than Democrats do, according to a new Pew Research Center survey, opening up the widest partisan gap on American opinion on Israel since available polling in the late 1970s.

In a survey taken July 8-14, as Israel started bombing Gaza, 51 percent of American respondents said they sympathized more with Israel than with the Palestinians, compared with 14 percent who sided more with the Palestinians.

But the partisan breakdown was stark. Though 73 percent of republicans said they sympathized more with Israel, just 44 percent of democrats felt that way. According to Pew, “dating back to the late 1970s, the partisan gap in Mideast sympathies has never been wider.”

Among ideological groups, conservative republicans sympathized with Israel over Palestinians by a 77-percent to 4-percent margin. In contrast, just 39 percent of liberal democrats said they sympathized with Israel, compared with 21 percent who said they sympathized more with Palestinians.

The widening partisan gap is difficult news for the American Israel Public Affairs Committee, a lobbying group that attempts to influence policy between Israel and the United States by making support for Israel into a bipartisan issue.

But as conservative republicans continue to push the party into an increasingly pro-Israel direction, liberals who believe that U.S. policy is too reflexively supportive of Israel and too unsympathetic to Palestinians are gaining influence within the Democratic Party.