While candidates stump in Iowa, voters already have opened the 2008 presidential race by casting absentee ballots in nearly a dozen other states. Iowa’s first-in-the-nation caucuses are Thursday. But residents of 11 states — Alabama, Delaware, Florida, Georgia, Illinois, Michigan, Missouri, New Hampshire, New Jersey, South Carolina and Utah — have been able to vote for their favorite candidates since December.The first was Michigan, where absentee ballots were made available Dec. 1 for the Jan. 15 primary.