DES MOINES, Iowa — Uplifting appeals largely replaced stinging insults Tuesday as Democratic and Republican candidates did the only thing left to do in Iowa races that are too close to call — encourage supporters to vote for them.

"The polls look good, but understand this — the polls are not enough. The only thing that counts is whether or not you show up to caucus," Democrat Barack Obama told a fired-up crowd of young and old packed into a high school gymnasium.

Amid murmurs of "Amen!" at a pizza parlor in Sergeant Bluff, Republican Mike Huckabee urged hundreds: "Don't go alone. Take people with you. Fill up your car. Rent a van. Hijack your church's bus, whatever you've got to do to get people to the caucus who are going to vote for me."

Candidates made the pitch repeatedly as they canvassed the state for Thursday's caucuses, the first votes of the presidential nominating process. At least 130,000 Democrats and 80,000 Republicans are expected to participate in 1,781 neighborhood meetings at schools, fire stations and community centers across Iowa on what is forecast to be a clear but cold night.

New polls show both races competitive, the outcomes extraordinarily unpredictable.

Among Democrats, Obama, a U.S. senator from Illinois, is fighting with Sen. Hillary Rodham Clinton of New York for the lead as former Sen. John Edwards of North Carolina gives them strong chase. Two former governors, Huckabee of Arkansas and Mitt Romney of Massachusetts, are vying for first on the Republican side.

Given the tightness, turning out voters will be critical.

Thus, hordes of volunteers made thousands of get-out-the-vote phone calls Tuesday, the campaigns rolled out uplifting television ads and the candidates made their pitches on the first day of 2008. The efforts were intended to maximize media exposure and voter outreach.

There were signs that Democratic voters are more energized than Republicans.

Democrat Joe Biden, who ranks in the low single digits in polls, attracted 500 people to a noontime event at a Des Moines brewery — a bigger crowd than any Republican candidate usually gets.

Obama's campaign drew at or over capacity crowds. When he asked for a show of hands, many people said they'd never been to a caucus. In a boost for Obama, Democrat Dennis Kucinich asked his supporters to support Obama if he doesn't meet the cutoff point for voting in the caucuses.

As they campaigned in Iowa, all but one candidate, Romney, shunned the negativity that spiked in recent weeks.