Senators are on the verge of approving sweeping legislation to remake the nation’s immigration system for the first time in a generation by spending tens of billions of dollars to bolster security along the U.S. southern border and offering a path to citizenship for millions of illegal immigrants. Senators cleared the final procedural hurdle at midday and plan a final vote in the afternoon. Republicans opposed to the legislation blocked a final attempt Wednesday night to hold votes on 32 more amendments to the 1,100-page bill that the bill’s supporters hoped might earn more GOP votes for the measure.