Obama appears to have won the most states, picking up victories in Illinois, Idaho, Colorado, Minnesota, Connecticut, Utah, North Dakota, Kansas, Delaware and the Southern states of Georgia and Alabama, according to exit poll analysis.
Clinton Wins California Primary
Clinton won the delegate-rich states of California and New York, the largest and second-largest states to vote tonight. Clinton has also picked up victories in Massachusetts, New Jersey, Arizona, Oklahoma, Tennessee and Arkansas, where she and her husband have deep roots.
A record number of Hispanic voters turned out to the polls in California, according to preliminary exit polls -- a key demographic targeted by Clinton.
The bellwether state of Missouri is too close to project; with 99 percent of the vote in, Obama appears to be leading Clinton by only 7,000 votes.
At a rally in Chicago, Obama delivered a swipe at Clinton, telling supporters the race was between him and a candidate who accepts money from "special interests in Washington."
During her speech tonight to supporters in New York, Clinton struck a different tone, congratulating Obama on his victories.
"I look forward to our campaigns and our debates about how to leave this country better for the next generation," she told supporters who cheered her.
The Clinton campaign has vowed to fight on and campaign in high-delegate states like Ohio, Texas and Pennsylvania that vote in March and April. Meanwhile, Obama's campaign is taking its fight to Washington, D.C, Virginia and Maryland -- states that vote next Tuesday.
"We feel like we've had a good night, but this contest is far from over," Clinton's chief strategist Mark Penn told reporters tonight.
Obama campaign manager David Plouffe countered: "We're having an outstanding night. We're ahead currently in the number of states won ... and we think the delegates are very close."
Clinton Boosted by Women's Turnout
In an encouraging sign for her candidacy, Clinton won Massachusetts despite recent endorsements by Massachusetts Sens. Ted Kennedy and John Kerry.
Exit poll results suggested Clinton owes her victory in the Bay State to a large turnout by women and a sizable gender gap -- with more women supporting Clinton and more men supporting Obama. Her victory in New Jersey is also being credited to a high turnout of women who supported her, according to exit poll analysis.
In his home state of Illinois, though, exit polls indicated that Obama claimed the majority of votes cast by white women, Clinton's core group in most states. In Georgia, 88 percent of the record turnout of black voters backed Obama, according to preliminary exit poll results, mirroring Obama's success among black voters in South Carolina.
McCain Emerges as GOP Front-Runner
On the Republican side, McCain, securing his status as the clear GOP front-runner, won California, New York, Illinois, Arizona, Connecticut, Delaware, Oklahoma, New Jersey, and the classic bellwether state of Missouri, which has an excellent record for predicting political winners.
Huckabee has also done better than expected, winning a surprise victory in West Virginia, winning Alabama, Tennesee Georgia, and his home state of Arkansas, based on exit poll analysis. Former Massachusetts Gov. Mitt Romney won victories in Colorado, Utah, Minnesota, North Dakota, Montana and Massachusetts, according to exit poll analysis.
Historic, Emotional Democratic Race
The Democratic race is a heated contest between Clinton, whose once commanding lead in key states diminished as Super Tuesday approached, and Obama, the charismatic senator who had mega-star supporters like Oprah Winfrey, Caroline Kennedy and California first lady Maria Shriver stumping for him this weekend.
Preliminary exit poll results suggest Obama's message of "change" resonated with Democratic voters today; they were twice as likely to say they are interested in the candidate who can best "bring needed" change over the candidate with the best experience and other attributes.
Hispanics and women -- two key demographics targeted by Clinton -- turned out in high numbers, according to preliminary exit poll results.
Clinton vs. Obama in Homestretch
But with the way results were shaping up, those looking for a clear front-runner to emerge in the Democratic race could be waiting for months.
"They're in a real dogfight," California-based Democratic strategist Bill Carrick told ABC News. "It's really going to be about who can grind it out, who can raise money and stay in the game the longest."
Both campaigns were managing expectations today, with Plouffe defining victory for Obama as being "close" to Clinton in pledged delegates by the end of the night, reports ABC News' David Wright and Sunlen Miller.
Meanwhile, Clinton's chief strategist Mark Penn told reporters even if Obama finishes the day having won more delegates, they are confident Clinton will maintain an overall delegate lead including superdelegates.
Battle for Delegates and Votes
Both the Clinton and Obama campaigns have vowed to fight all the way to the convention.
"We're both preparing for a long, drawn-out affair," Plouffe said today. "If it goes through June, it goes through June."
"We are looking at a fight that is going to go, as we've said, well beyond tomorrow, possibly decided in March, possibly decided in April, possibly not decided until the convention," Clinton's communications director Howard Wolfson said Monday.
Delegate War
In interviews on Tuesday morning, Clinton said she hopes to win the delegate war.
"Right now I am ahead in both the popular vote and in delegates; I hope I stay there," Clinton told ABC News' Robin Roberts on "Good Morning America."
At stake today are 1,681 convention delegates — 87 percent of the total needed to clinch the Democratic nomination.
Obama and Clinton are poised to split delegates in contests across the country because Democratic Party rules allocate most of the delegates proportionately. The delegates will be awarded to the contenders based on their shares of the popular vote.
"Right now between Clinton and Obama, she's got a 60-vote delegate lead," ABC News' George Stephanopoulos told Diane Sawyer on "GMA."
"If that lead goes below 60 tonight, if Barack Obama closes the gap, he's going to have the edge," he said. "If she gets [her delegate lead] over 125, she's going to be hard to stop."
Hot Races to Watch
Tuesday afternoon, Obama attempted to lower expectations for tonight's Super Tuesday results as he cast his balllot blocks from his South Side Chicago home.
"I still think Sen. Clinton is the favorite. She had 20-30-point leads in many of these states, we've been closing some ground," Obama said inside an elementary school. "My guess is we'll have a good night and we'll probably end up having a split decision."
Clinton and her husband, former President Bill Clinton, cast their votes early this morning in Chappaqua, N.Y.
"It's a very humbling and overwhelming experience to cast my vote today," she said.
After celebrities like Oprah Winfrey, California first lady Maria Shriver, Caroline Kennedy and Robert DeNiro stumped for Obama over the weekend, Clinton unleashed her own star power today with a robocall starring Oscar-winner Jack Nicholson.
"She never gives up, she never gives in and she's battle-tested," Nicholson says in an automatic call to Californians today. "She'll be a strong commander in chief, she has the experience to deal with the economic challenges we face as a nation today and in the future."
Final Pitch
The two candidates made their final pitches to voters Tuesday morning in dozens of satellite television interviews.
"With two wars abroad and a looming recession, people need a president who's ready on Day One to be commander in chief and to turn the economy around. We also need a candidate who will be able to win in November," Clinton said on "Good Morning America."
Obama told Sawyer: "We're seeing that the American people are understanding, unless we change how things work in Washington — reduce the power of special interests and get our economy back on track — that a lot of people are going to be hurting."
Many Democratic voters had to rethink their ballots when former Sen. John Edwards abandoned his presidential bid last week after failing to win one primary or caucus.
The race has ignited record Democratic voter turnout in the early primary and caucus voting states and today.
But with high interest and two popular candidates splitting delegates from across the country, political analysts say it could be months before either Clinton or Obama emerges as the victor.
"This is going to go on for a while," Carrick said. "It's just going to be trench warfare."
