DAVENPORT, Iowa - Rep. Tom Tancredo started barnstorming through eastern Iowa on Thursday, talking immigration to religious conservatives and stepping up his flirtation with the 2008 presidential race.The Littleton Republican arrived in Moline, Ill., then made the short drive across the Mississippi River into Davenport.Iowa is home to the first presedential caucuses in 2008, and Tancredo wants the big-name contenders to take up his crusade to stop illegal immigration."If you don't approach this thing as if you are completely serious, you can't accomplish any goal," he said.