Republican John McCain insists last year's US troop buildup in Iraq brought a glimmer of "something approaching normal" there, despite a recent outbreak of heavy fighting and an American death toll that has surpassed 4,000. "We are no longer staring into the abyss of defeat, and we can now look ahead to the genuine prospect of success," McCain said in a speech prepared for delivery Monday. The presidential nominee-in-waiting is closely tied to the unpopular, five-year-old war. McCain was a vocal advocate of the troop increase strategy eventually adopted by President George W. Bush, and is seeking to convince people the strategy is working. In either Hillary Clinton or Barack Obama, McCain will face a potential Democratic rival who disputes the claims of success and seeks a swift withdrawal of US troops. Debate will intensify this week as Gen. David H. Petraeus, the top commander in Iraq, and Ambassador Ryan C. Crocker testify to Congress. Clouding their testimony is the fighting that erupted late last month as US-trained Iraqi forces attempted to oust Shiite militias from Basra in southern Iraq.