[cnn-photo-caption image= http://i2.cdn.turner.com/cnn/2008/POLITICS/06/11/dems.evangelicals/art.obamageneric.gi.jpg caption="Gore has ruled out a run for any office but President."]
WASHINGTON (CNN) - Four years ago, Michael Farris was knee-deep in presidential politics.
Early in the 2004 primary season, he got a call from the Republican National Committee: Would he be willing to mobilize his grass-roots army on behalf of President Bush's re-election effort?
By May that year, his organization, Generation Joshua, was deep into fall planning mode. It had laid the groundwork for an ambitious turnout operation for the general election.
Action teams of young volunteers soon fanned out over the major swing states, spearheading get-out-the-vote efforts, part of an evangelical machine that kept the GOP competitive in the ground game unions and other Democratic groups typically dominate.
In one three-day span, the members of Generation Joshua knocked on more than 15,000 doors in the crucial state of Pennsylvania.