Barack Obama and Hillary Rodham Clinton heaved toward the finish line in their exhaustive Democratic presidential odyssey with Obama poised to claim victory and Clinton facing the prospects of having to abandon a quest that once seemed a sure shot but became one of long odds.And although Tuesday's primary-season ending contests in South Dakota and Montana won't decide the Democratic nomination, the closing of the polls could open the floodgates to dozens of superdelegates - members of Congress and other party leaders - long anxious to throw their support to Obama.That could decide the nomination in a matter of days."Once the last votes are cast, then it's in everybody's interest to resolve this quickly so we can pivot. We're less than three months away from our convention. So we've got a lot of work to do in terms of bringing the party together," the Illinois senator said in an interview with The Associated Press on Monday as he campaigned in Michigan, a general-election battleground.Obama said there were a lot of superdelegates who have been private supporters of his but wanted to respect the process by not endorsing until the final primaries were done.And while both candidates forged ahead on Monday in full-bore campaigning, neither Obama nor Clinton planned to be in either primary state on election night.In a defiant shot across the GOP bow, Obama, who returned to hometown Chicago late Monday, planned to hold his wrap-up rally in St. Paul, Minn., at the arena that will be the site of the Republican National Convention in September.Clinton returned to New York, the state she represents in the Senate, planning an end-of-primary evening rally in Manhattan after a grueling campaign finale as she pushed through South Dakota on Monday.The former first lady has given no hint of quitting the race, and she has said repeatedly she may continue her candidacy even beyond the end of the primaries."I'm just very grateful we kept this campaign going until South Dakota would have the last word," she said at a restaurant in Rapid City in one of her final campaign stops. Polls suggested Obama would win both South Dakota and Montana.She still sounded buoyant. Her biggest booster and most tireless campaigner, husband Bill Clinton, didn't. "This may be the last day I'm ever involved in a campaign of this kind," the former president said somberly as he stumped for her in South Dakota.Ahead of Tuesday's concluding primaries, Obama sought to set the stage for reconciliation, praising Clinton's endurance and determination and offering to meet with her - on her terms - "once the dust settles" from their race."The sooner we can bring the party together, the sooner we can start focusing on John McCain in November," Obama told reporters in Michigan. He said he spoke with Clinton on Sunday when he called to congratulate her on winning the Puerto Rico primary, most likely her last hurrah.That fueled speculation for a "dream ticket" in which Clinton would become Obama's running mate - but neither camp was suggesting that was much of a possibility.In the AP interview, Obama was asked when he would start looking for a running mate."The day after I have gotten that last delegate needed to officially claim the nomination, I'll start thinking about vice presidential nominees. I think it's likely to come this week," he said. "It's a very important decision, and it's one where I'm going to have to take some time."Robert Gibbs, a top Obama aide, said late Monday the seemingly endless Democratic contest could be resolved "in the next 24 to 48 hours.""You're going to have a lot of superdelegates come out," he said.Clinton left South Dakota for New York late Monday, the final leg of a whirlwind four days that took her from New York to Puerto Rico, to South Dakota and back. For a campaign pushing against long odds, it was a show of determination.The former first lady, suffering from a recurrent cough, had to cede the microphone to her daughter twice during the day as she struggled to recover her voice. Chelsea promptly took the opportunity - to discuss health care.Meanwhile, Obama's aides prodded uncommitted lawmakers and other superdelegates to climb aboard quickly - as Clinton struggled to hold back the fast-rising tide.Democratic officials said that if Obama failed to gain the needed 2,118 delegates by Tuesday night, one possibility under discussion was for Senate Majority Leader Harry Reid and Speaker Nancy Pelosi to issue a statement on Wednesday urging superdelegates to state their preferences as soon as possible.