Moderate Republicans have given a lot of ground to conservatives in immigration negotiations, but it’s the one matter where they’ve refused to negotiate that is likely to sink a compromise bill the House is scheduled to vote. The bill — negotiated in recent weeks by members representing the various GOP factions — provides a path to citizenship for so-called Dreamers, young undocumented immigrants brought to the U.S. as children. But it doesn’t change current law to prevent Dreamers from sponsoring visas for their parents once they become citizens. Several conservatives say they can’t vote for the bill — with some predicting the legislation will fail — if the bill is not changed to block Dreamers from sponsoring their parents for legal status. But moderates aren’t willing to negotiate over that, especially after they’ve given conservatives so many other things they wanted in the bill.