DES MOINES - As you know, the Iowa caucus is the first crucial step in the road to the white house. Here's a look at what we'll be following tonight.

For the democrats, polls show Hillary Clinton, John Edwards and Barack Obama are locked in a tight three way battle for first place.

Second tier candidates including Joe Biden, Chris Dodd and Bill Richardson are hoping they can turn some heads tonight to keep their campaigns alive.

As for the republicans, it looks like it will be a two man race for the top spot between Mike Huckabee and Mitt Romney.

Behind them, Rudy Giuliani, John McCain, Ron Paul and Fred Thompson are looking for some kind of momentum for next week's New Hampshire primary.

Unlike a primary, actual voting happens in a short period of time tonight. So for much of today, the campaign continued through Iowa.

The democrats spent the last few hours before the caucuses going around and talking to as many people as they can.

Senator John Edwards held a rally late last night that included a performance from John Mellenkamp. Edwards has used Mellankamp's music throughout his campaign.

Senator Hillary Clinton made a quick stop at a local restaurant in Des Moines earlier this afternoon. Her daughter Chelsea, and her husband, former president Bill Clinton joined her.

And, Senator Barack Obama spent some time at a Des Moines food court chatting with potential caucus goers. His wife, Michelle was there too. Democratic Party leaders say they know it's a tight race between the top three.

"I think a lot of it is going to be turnout. Who really gets people to turnout. We see so much excitement and energy. The weather's going to cooperate. So we think there's going to be very nice turnout," said Scott Brennan, Iowa Democratic Party Chair.

Experts say this is one of the most intense races in history. A win here in Iowa will push the top candidate one step closer to the presidency.

On the republican side, Mike Huckabee left Iowa yesterday to appear on the Tonight Show with Jay Leno. But today he was back in eastern Iowa making his final campaign stops. During this stop in Burlington, Huckabee urged supporters to attend the caucuses and to ask their friends to attend as well. He told them not to be tempted to stay home to watch the Orange Bowl, joking that it would be a boring game anyway.

As for the rest of the republican field, the candidates in Iowa stuck close to Des Moines today where the results will come in tonight.

We mentioned a little earlier how second tier candidates need to make a splash to keep their campaigns on track. Some of those candidates say they have no plans to back down.

Congressman Ron Paul enjoyed a mid-afternoon lunch in a Des Moines deli. His poll numbers are low, but the republican says polling hasn't reached his supporters. And they're coming out of the woodwork.

"It's hard for me to believe that we won't do better than the projections that some of the polling," said Paul.

The caucuses are all about expectations. Doing better or worse than the experts predict can make or break a campaign. A second tier candidate like former Tennessee senator Fred Thompson can finish third and celebrate the caucuses.

"The crowds have been better and better and the enthusiasm has been building and building," said Thompson.

A top three finish means candidates have a real chance to win the nomination. No one has ever become the party's choice without finishing in the top three. That is why every one of Iowa's one thousand 781 precincts matter. And candidates like Mitt Romney cannot afford to rest.

"Politics has become a profession not a duty. I want you to know politics is not my profession," said Romney.

Republican race has two front runners - Romney and Huckabee. But anyone can grab that coveted third place finish. And from there anything can happen.

"The dynamics this year are so different. We've never seen anything like this," said Chuck Laudner, Executive Director, Iowa Republicans.

These caucuses will be unlike anyone before them. There are 16 candidates in two parties. And more than a fourth of them really have a serious shot at becoming the next president of the United States.

Candidates won't have much time to rest between tonight and the first primary, which is on Tuesday in New Hampshire. That first primary for both parties could show how much tonight's Iowa results affect the rest of the nation.

Over the next several weeks, primaries and caucuses will take place in a handful of states before the next major test, what has being dubbed "Super Duper Tuesday."

That's when 21 democratic and 19 republican races will be held, including two of the largest states, California and New York.