PHILADELPHIA - The primaries in North Carolina and Indiana today offer Barack Obama and Hillary Rodham Clinton one more chance to transform their long and bitter struggle for the Democratic presidential nomination.

Results from what is the most delegate-rich day left on the primary calendar could close the deal for Obama, give a major boost to Clinton, or leave the race about where it has been -- with Obama ahead but not yet able to nail down the prize.

Late polls gave Obama a single-digit lead in North Carolina and Clinton a similar advantage in Indiana. In television interviews Monday, both candidates said they expected the contest to go on no matter what happens Tuesday.

"I want your vote, I want it badly," Obama told employees of an electronics company in Durham, N.C. "The question you have to ask is who can best deliver on the promise to bring change."

Clinton said to a crowd in High Point, N.C.: "I am running because I think with all my heart that I am best prepared to be the president and I am the stronger candidate to take on (Republican) John McCain in the fall."

Should Obama win both North Carolina and Indiana, where a combined 187 delegates are at stake, the race would be all but over, whether Clinton acknowledged it or not.

Many of the undecided superdelegates, including some of the more prominent ones, would likely start lining up behind Obama and talking about the need to prepare to take on the Republicans.

Two victories by Clinton, though, would undermine Obama's claim to the nomination, reinforce doubts about his electability, and bolster her argument to the superdelegates that she is the party's better bet against McCain in November.

A split, with Obama prevailing in North Carolina and Clinton in Indiana, is the most likely outcome, according to the polls.

While not a game-changer nor a game-ender, a divided outcome would help Obama run out the clock, putting him that much closer to 2,025 delegates _ the magic number needed to nail down the nomination _ and making the arithmetic for Clinton that much more daunting.

The 2,025 number does not take into account the disputed and currently unrecognized delegations from Michigan and Florida, where primaries were held earlier than party rules allowed.

Clinton won both, although no candidates campaigned in either state and Obama's name wasn't on the Michigan ballot. A Democratic National Committee panel is to address the predicament of both states May 31.

After Tuesday, the focus of the campaign will be less about the six primaries that remain and more about the superdelegates, the party- and elected-officials who get to attend the party convention in Denver by virtue of their positions.

Only 217 pledged delegates are at stake in the primaries after Tuesday _ and they will be allocated on a proportional basis _ compared to about 270 superdelegates who have yet to endorse a candidate.

The primaries end June 3, and party chairman Howard Dean has asked all superdelegates to state their preference by the end of June.

Obama, since his nine-point defeat in Pennsylvania two weeks ago, actually has fared better than Clinton among superdelegates. He has picked up 19 to her 11, including two more from Maryland on Monday, all of this despite the reemergence of the Rev. Jeremiah A. Wright Jr. as a major problem for his campaign.

Overall, Obama leads Clinton 1,745.5 to 1607.5 in total delegates, according to the Associated Press.

The final week leading up to today's primaries was dominated by a debate over Clinton's proposal to repeal the federal gasoline tax for the summer and make up the difference through a windfall-profits tax on the oil companies. Both measures would require congressional approval.

Clinton, who is described in her new television commercial as "the candidate that is going to fight for working people," said that the savings to drivers, while modest, would make a difference.

"I believe we should start standing up for the vast majority of Americans who are paying these outrageous gas prices," the New York senator said in High Point.

Obama has called the proposal "political pandering," and "a perfect metaphor" for politics as usual.

Said the Illinois senator at his Durham appearance: "The question is `Are we going to keep on doing what Washington does?' _ which is to use gimmicks to get you through the next election _ or are we going to say, `This time it's going to be different?'"

In North Carolina, which has 115 pledged delegates, Obama is counting on winning the overwhelming share of an African-American turnout that could amount to one-third of the total vote.

In Indiana, with 72 pledged delegates, Clinton is banking on her strength among the white, blue-collar voters and older women who have helped her win key primaries in Ohio and Pennsylvania.

Both candidates campaigned in North Carolina and Indiana on Monday.

The next primary after today is West Virginia on May 13, followed by Oregon and Kentucky on May 20, Puerto Rico on June 1, and Montana and South Dakota June 3.

(c) 2008, The Philadelphia Inquirer.

Visit Philadelphia Online, the Inquirer's World Wide Web site, at http://www.philly.com/

Distributed by McClatchy-Tribune Information Services.

A service of YellowBrix, Inc.