With the races too close to call, candidates spent their last full campaign day before the Iowa caucuses urging voters for their support.
Tuesday, volunteers spent most of their time making telephone calls and going door to door to get out the vote.
One poll says Senator Hillary Rodham Clinton and Mitt Romney are leading. Another says Senator Barack Obama and Mike Huckabee are ahead. Many voters haven't locked in their support yet.
Republican Huckabee heads to Los Angeles Wednesday to tape the "Tonight Show with Jay Leno."
Democrat John Edwards will appear at a free concert by John Mellencamp. The former North Carolina senator is on a 36-hour push that he calls a marathon for the middle class.
Clinton takes to the airwaves, with a televised message airing on every media market in Iowa. Obama is also going to television with a longer-than-usual two-minute ad.