WASHINGTON—The Senate headed toward a vote Friday advancing a Republican measure to fund the government through September, as heartsick Democrats implored Senate Minority Leader Chuck Schumer (D., N.Y.

Donald Trump congratulated Chuck Schumer for his decision to advance a GOP bill to keep the government open — but it’s hardly the kind of praise that the Senate Democratic leader needs. Fellow lawmakers and party activists are irate at what they see as a massive cave to Republicans as a time when