As the violence in Iraq continues despite greater troop presence, Democratic strategists see Republican candidates facing an increasingly daunting task of keeping the White House after 2008. Most vulnerable, insiders say, is John McCain, the staunchest supporter of the war among GOP candidates. Once seen as the inevitable GOP nominee, his campaign is faltering badly. While plenty believe he'll turn his luck around--his campaign staff is stocked with former Bush campaign people--others see it as nearly finished. "The general feeling around town is that McCain is done," says a strategist with a top Democratic consulting firm. "And if any Republican...