Democrats in Congress may need redemption with voters next year. But can President Obama save them? Some strategists believe replicating the model that produced Democratic gains in the past two election cycles--a combination of mobilizing new voters and independents, along with an energized party base--is the answer. Victories over the past four years even convinced some an enduring Democratic majority had emerged. President Obama's 2008 win only punctuated that ascendancy. Others believe dancing on the Republicans' grave is premature. Sinking the GOP was an easy target when the party had controlled the White House since 2001. Republican unpopularity--in an environment...