Voters head to the polls in Indiana and North Carolina this morning with the candidates hoping for a knockout victory, but anticipating yet another split decision .
"Today is likely to be Groundhog Day. It's most likely to be six more weeks [of campaigning] because we're going to see a split," said ABC News' George Stephanopoulos on "Good Morning America".
Stephanopoulos told "GMA" Tuesday that Sens. Hillary Clinton, D-N.Y., and Barack Obama, D-Ill., tried to downplay expectations.
Obama's supporters suggested to Stephanopoulos that Clinton would win in Indiana by as much as eight points, and Clinton's camp hinted that Obama would win by as much as 10 points in North Carolina.
If either of those margins are trimmed, the loser will likely claim some sort of upset victory.
With 187 delegates up for grabs, it's a high-stakes moment for both campaigns where an upset by either candidate could be decisive -- not so much in pledged delegates, but in making closing arguments to superdelegates, the party insiders who will ultimately decide who the Democratic nominee will be.
"If he wins both that could end it; if she wins both, that could be a game changer," Stephanopoulos said.
Each candidate sought star power for a last-minute boost.
Clinton appeared on "The David Letterman Show" Monday night, giving the Top 10 reasons why she loves America.
With a nod to Letterman's frequent mockery of her attire, Clinton joked with the Hoosier State native that the Number 8 reason she lovs America is "Thanks to the Internet, I can order new pantsuits 24/7."
Stevie Wonder serenaded Obama supporters in Indianapolis, hoping the nomination will be signed, sealed and delivered for his man.
"Barack will be president and that ain't no lie," Wonder sang before the crowd of 21,000.
Both candidates worked late into the night.
"We've got to have a plan," Clinton told voters in New Albany, Indiana, Monday night. "You don't just send everybody into the field and have them running in all directions. Here's what we are going to do. Defense. Offense. Lets win for America!"
Obama attacked Clinton as a phoney for her new campaign rhetoric about changing antitrust law to sue the Organization of the Petroleum Exporting Countries or OPEC, the 12-member nation organation that sets worldwide oil production.
"You say you've been in the White House for eight years, you've had two terms as U.S. Senator and haven't said a word about OPEC and now suddenly you're gonna take it right to OPEC?" he said. "When you've opposed fuel efficiency standards that would actually reduce demand for oil and put OPEC in a bind? That's not being straight with the American people. That's not the kind of politics we believe."
There remains a lot of undecided voters, but it's time to get off the fence.
After talking to her husband and reading the Indianapolis Star, which has endorsed Clinton, Shelly Zoran of Indianapolis chose Clinton.
"I just decided within myself that I thought her experience was good," Zoran told ABC News.
For Jim Birge how the candidates are campaigning mattered.
"I was originally supporting Hillary Clinton, but I like how Obama is running his campaign much better than the way [she] has run her campaign. She's been more negative. I think she's been more divisive," Birge said.
Some voters like Brenda Kenyon say they still haven't decided and say it may even come down to flipping a coin.