John Kerry's (search) rivals hoped to slow his momentum Tuesday as voters went to the polls in the first round of multi-state contests to determine which candidates have what it takes to be nationally competitive.

Polls showed the Massachusetts senator leading in five of the seven states, gaining on Sen. John Edwards (search), D-N.C., in South Carolina and in a virtual tie with retired Army Gen. Wesley Clark (search) in Oklahoma.

"At the end of the day I would suspect we'll be talking about a pretty big day for John Kerry, if not a perfect day for him," pollster John Zogby told Fox News. Polls showed Kerry with solid leads in Missouri, Arizona, New Mexico, Delaware and North Dakota.

"I'm ready," Kerry said as he left Phoenix for a round of campaigning in Washington state. "I'm looking forward to today, tomorrow and all the days after that."

For more on the campaign, click to view Foxnews.com's You Decide 2004 page.

But a clean sweep Tuesday night seems unlikely to some observers.

"I don’t think that's going to happen," former Democratic National Committee Chairman Don Fowler told Fox News. "If he wins five and comes close in two others, that's going to be good for him but that certainly keeps Edwards alive and active in this campaign."

In Tuesday night's contests, 269 pledged delegates were at stake. Kerry, enjoying momentum from big wins in Iowa and New Hampshire, is now winning the race for delegates, having leapfrogged former Vermont Gov. Howard Dean by winning unpledged "superdelegates." According to a survey by The Associated Press, Kerry had 115 delegates to 114 for Dean. The other candidates lag far behind.

Going After the Front-runner

Tuesday's contests were expected to winnow the field of major contenders, from seven perhaps all the way down to two. Edwards was counting on a South Carolina win to keep his own campaign alive.

Edwards declared, "I'm going to win tonight."

"I think this South Carolina primary is a head-to-head contest on who can compete in the South, who can win rural voters and who can do well with African-American voters, and we're going to find out the result of that later tonight," Edwards said Tuesday in Clinton, S.C.

When asked by reporters if he could carry on without a Palmetto State victory, Edwards said, "I'm running a national campaign. If I win here on Tuesday, as a practical matter, we're probably down to a two-person race."

Although South Carolina and other southern states are traditionally conservative Republican territory, Edwards has been trying to convince voters he knows what's best for the region.

"The south is not George Bush's backyard — it's my backyard, and I will beat George Bush in my backyard," Edwards said again Tuesday in an oft-repeated speech.

South Carolina Gov. Mark Sanford told Fox News that Edwards is sure to give Kerry a run for his money.

"There's been a certain energy to his campaign that suggests maybe he'll win it tonight and maybe he'll win it stronger than people are anticipating," Sanford, a Republican, said.

But Edwards likely needs to watch his back.

"So far, Kerry's close has been very significant," said Democratic pollster Carey Crantford in South Carolina, noting that while Kerry's support in the state was in the teens last week, he was only 5 points behind Edwards in polls released on Monday.

"It's going to go down to the wire. So far, Edwards has been able to maintain a significant lead, and we'll see how it ends up," Crantford said. "Edwards' message really hits home here in South Carolina," but Kerry has "significant electability."

Clark, a native of Arkansas and the only other Southerner in the race, was hoping for a win in Oklahoma and a respectable showing in both Arizona and New Mexico to propel his campaign to the next round.

In Oklahoma City, Clark made another broad appeal to veterans at a ceremony in the statehouse before visiting cafes and pizza parlors to ask patrons for their votes.

"I don't think there's anybody running for this office or in office who knows any more about the United States Defense Department and defense budget than I do," Clark told the veterans. "But our country is not made strong by weapons systems. It's made strong by the courage and the honor and the skill and the dedication of our men and women in uniform."

At Clark's Oklahoma City headquarters, the candidate's 34-year-old son, Wesley Clark Jr., told reporters he wanted his father to quit the race if he did not win Oklahoma.

"It's really been disillusioning. You go out and see the way politics really works. It is a dirty business filled with a lot of people pretending to be a lot of things they are not," Clark Jr. said.

One-time front-runner Dean looked beyond the Feb. 3 states of Arizona, Delaware, Missouri, New Mexico, North Dakota, Oklahoma and South Carolina, where he was not running any TV ads and where polls showed him badly lagging,  to later races to get his campaign back on track.

The former Vermont governor's campaign, which had severely cut back on spending, made another round of staffer layoffs, aides said Monday night.

Dean continued to attack Kerry, saying the senator's electability will become a real issue for him.

"His credibility is under enormous attack, repeatedly, he has this pattern — you saw it with No Child Left Behind, you saw it with the war, you see it with special interests, which I think is terribly damaging. It appears that his word is no good," Dean told reporters on his campaign plane.

But Kerry's campaign maintains that the senator is the most electable of the Democrats in a national contest.

"He's the only Democrat who has a consistent lead over Bush so those Democrats who are looking for an electable candidate are flocking to Senator Kerry," Mark Mellman, a senior Kerry consultant, told Fox News. Mellman said several recent national polls show that Kerry has an edge over Bush in head-to-head matchups.

On the Trail, Waiting for Votes

Edwards remained in South Carolina after wrapping up his campaign late Monday at a community rally in the town of Seneca, where he was born.

Battling a head cold, his voice hoarse, Edwards canceled a planned early-Tuesday morning visit to a Greenville polling place. He was to await election returns in Columbia before heading to Memphis, Tenn., late Tuesday.

Kerry and Dean were in Washington state, site of caucuses on Saturday. Clark was in Oklahoma.

Sen. Joe Lieberman (search), D-Conn., planned to do some last-minute campaigning in Delaware before returning to the Washington, D.C., area. Lieberman's campaign denied that the senator was considering dropping out of the race Tuesday night if he did not win any of the day's contests but officials said the campaign would regroup on Wednesday and likely make a decision then.

"It's up to the voters now. We've given them a message," Lieberman told reporters in Wilmington, Del. "I've been optimistic that we're going to get enough support around the country to keep this going."

The Rev. Al Sharpton (search) was the only other candidate expected to be in South Carolina.

Fox News' Kelly Wright and The Associated Press contributed to this report.