GRINNELL, Iowa (AP) _ Barack Obama is urging Iowa college students to head back to school early from the upcoming holiday break to support him in the January 3rd Democratic caucuses.

Obama notes that students who go to school in Iowa have established residency there and are able to take part in the vote.

Hillary Clinton is Obama's top rival in Iowa. She's criticized the effort by saying, ``That may be the way politics is played in Chicago, but not in Iowa.''

Obama has told students not to listen to the critics. The Illinois senator is polling well among young people in the state.

In appearances at Grinnell College and the University of Iowa, Obama told thousands of students that ``The winner of the Iowa caucus has got a huge head start in terms of being the Democratic nominee.'' He said their future and America's future are at stake.