With the final scramble to Super Tuesday in full swing, Sens. Hillary Clinton and Barack Obama started their day by making a final pitch to voters on network television.
Clinton told Robin Roberts on "Good Morning America" that with 22 states voting on the same day this year for the first time, no one knows how the extraordinarily tight race will shake out.
"It's unprecedented. We're all kind of guessing about what it's going to mean because it's never happened before," Clinton said on "GMA."
"Right now I am ahead in both the popular vote and in delegates — I hope I stay there," Clinton said. "It's intriguing and somewhat mystifying because none of us really understand what the impact of all these contests on one day will be for any of us."
Obama Attracts Celebrity Endorsements
Clinton downplayed her rival's spate of celebrity endorsements, including Sen. Ted Kennedy, Caroline Kennedy, Oprah Winfrey, California first lady Maria Shriver and the latest celebrity recruits — singer Dave Matthews and actor Robert DeNiro.
"Celebrity endorsements are intriguing, they're interesting, but they need a president who's going to be on their side. And with two wars abroad and a looming recession, people need a president who is ready on day one to be commander in chief and to turn the economy around," she said.
Obama's campaign got a boost in delegate-rich California, winning the endorsement of The Los Angeles Times and the state's largest Hispanic newspaper.
On "Good Morning America" Obama continued to position himself, as he has done throughout the campaign, as a Washington outsider intent on changing the status quo.
"American people are understanding unless we change how things work in Washington, unless we reduce the power of special interests and get our economy back on track, a lot of people are going to be hurting," Obama told ABC News' Diane Sawyer.
Obama responded to the Clinton campaign's recent suggestion that Obama would make a good vice presidential nominee.
"Right now we're in a pretty fierce contest and I think we're getting way too far ahead of ourselves when we start talking about vice presidential candidacies but I can tell you this, that's not something I'm running for," Obama said.
"If I were 20 points down, we probably wouldn't be hearing that. I think it's a sign that we're doing pretty well," Obama said.
In a tight race that has become a fight for delegates, Obama needs to win several key states to overtake Clinton.
"I want to look at three states tonight, especially for Barack Obama — Massachusetts, Missouri and California. These are all states where Hillary Clinton has had a big lead up until now. They are very close right now," Stephanopoulos said.
"If Barack Obama wins two out of three of those states, he's going to have the momentum, he's going to be hard to stop," Stephanopoulos said.
California Has Most Delegates
The make-or-break state this time is delegate-rich California, where officials are predicting a record turnout. About 700,000 more people have registered to vote in the state than did in 2004.
Clinton's lead in California has shrunk and her husband has been working the state in overdrive, holding campaign rallies and trying to mobilize voters.
Monday night Hillary Clinton appeared on the "Late Show With David Letterman" and cracked jokes about her husband's potential role in the White House.
"You know, in my White House, we will know who wears the pants suits," she said jokingly.
Meanwhile on the Republican side, former Massachusetts Gov. Mitt Romney has been jetting across the country, sporting an elephant tie to emphasize his message that he is the only true conservative in the race.
"Across the country, conservatives have come together and they have said 'you know what, we don't want Sen. [John] McCain,'" Romney said Monday.
McCain is going into Super Tuesday as the prohibitive Republican front-runner.
"We're guardedly confident. We think we can win. That's why we're campaigning hard virtually until the polls close," McCain said Monday.
Former Gov. Mike Huckabee is trailing McCain and Romney in the polls. He is hoping to pull off wins in a few Southern states like his home state of Arkansas.
"If McCain holds on to the biggest states where he has been competing, the winner-take-all states, New York, New Jersey, his home state of Arizona, Missouri, he's going to be very, very hard to stop," said Stephanopoulos.
"Mike Huckabee's going to win his home state of Arkansas tonight … and if he picks up another Southern state, he's hanging in," Stephanopoulos said.
ABC News' Claire Shipman and John Parkinson contributed to this story.