GOP leaders moved to ban President Obama from negotiating global warming policy and changes to U.S. immigration policy in any new trade deal, working feverishly Wednesday to secure final support as they prepare for a Friday showdown on granting the White House fast-track trade authority. The leaders’ decision to schedule the vote suggests they believe they have wrangled enough supporters to get the bill through — a test of both House Speaker John A. Boehner, who will have to deliver most of his GOP troops, and of Mr. Obama, who will have to deliver the backing of a dozen Democrats....