President George W. Bush, confronting a skeptical Congress and American public, sought to deflate strong opposition Tuesday to sending more troops to the war, asserting that "America must not fail in Iraq" and his plan offered the best chance of success. Facing a major political showdown over his policy, Bush said that "the consequences of failure would be grievous and far reaching." In his annual State of the Union address, Bush sought to revive his troubled presidency with proposals to expand health insurance coverage and slash gasoline consumption. But the war was issue No. 1. The White House released excerpts of his address in advance.