Looking to bring finality to the Democratic presidential campaign,worked furiously Monday to win over enough superdelegates to clinch the nomination with the final primaries Tuesday.
CBS News' Maria Gavrilovic reports that Obama spoke to superdelegates beginning Monday morning and will continue to do so on Tuesday.
Obama has 2,075 delegates, according to the latest CBS News count, 43 short of the 2,118 he needs to secure the nomination.
Obama is expected to reap a superdelegate harvest this week, CBS News correspondent Dean Reynolds reports. Sources tell CBS News that most of the 17 still uncommitted super delegates from the U.S. Senate are expected to endorse Obama shortly-along with at least a dozen House members.
Obama wants to formally kick off his general election campaign against Republicanin a victory speech Tuesday night as the final primary campaign polls close in South Dakota and Montana.
"Senator Obama is trying to line up people that are going to come out for him tomorrow during the day so that he'll have enough that puts him over the top that he can declare victory tomorrow," said Pennsylvania Rep. Jason Altmire, one of about 200 superdelegates under pressure to take a side in the contest.
"He apparently is telling people that he has the numbers, and that's what's going to happen, at which point it would become moot what the rest of us do," said Altmire, who added that he will wait until after the final votes and make a decision by week's end.
According to communications director Robert Gibbs, the Obama campaign is confident that all superdelegates will make a decision within the next 48-72 hours.
On the final day before the last primaries, Obama told voters in Michigan that he andwill be working together in November despite fears by some that the Democratic Party will be divided after the long and bitter primary campaign.
Claiming Clinton has run an outstanding race, the Democratic front-runner said to applause that Clinton and he will be "working together in November." He did not elaborate.
Clinton campaigned in South Dakota, telling the patrons at Tally's Restaurant in Rapid City: "I'm just very grateful we kept this campaign going until South Dakota would have the last word. What South Dakota decides tomorrow will have a big influence in what people think going forward."
Her husband, former President Clinton, gave a clearer signal that the primary race is over.
"I want to say also that this may be the last day I'm ever involved in a campaign of this kind," Bill Clinton told voters in Milbank, S.D., a small town in northeast South Dakota.
South Dakota and Montana are the last Democratic nominating contests, and Obama is favored in both states.
Obama has made up most of the ground he lost Saturday when the national party's rules committee agreed to reinstate delegates from Michigan and Florida. The party had initially refused to seat the delegates as punishment for scheduling their contests in violation of party rules.
With 31 delegates at stake Tuesday, Obama could close the gap further and cue undecided superdelegates to come to his side.
But Clinton argues she now leads in the popular vote - a debatable point given that she relies on Michigan and Florida outcomes. None of the candidates campaigned in either state and Obama received no votes in Michigan because he removed his name from the ballot. Clinton also continues to present herself as better able to confront McCain in the fall.
She and her campaign's national chairman, Terry McAuliffe, made it clear that Obama's supporters were now fair to pluck with those arguments.
Clinton invited Virgin Islands superdelegate Kevin Rodriguez, a recent convert, to travel with her to South Dakota where she planned to campaign Monday. Rodriguez had initially supported Clinton, switched to Obama, and recently returned to her camp.
"This has been such an intense process," she said, "I don't think there has been a lot of time for reflection. It's only now that we're finishing these contests that people are going to actually reflect on who is our stronger candidate."
Asked Monday on CBS' "The Early Show" if Clinton would take her campaign to the convention, McAuliffe said again they
Cinton's decision, if prolonged, is not likely to sit well with party leaders and some of her own supporters. House Speaker Nancy Pelosi, D-Calif., and Senate Majority Leader Harry Reid, D-Nev., have both called on the contest to end shortly after the final primaries.
Tom Vilsack, the former Iowa governor and a national co-chairman of Clinton's campaign, said Sunday: "It does appear to be pretty clear that Senator Obama is going to be the nominee. After Tuesday's contests, she needs to acknowledge that he's going to be the nominee and quickly get behind him."
Clinton said she was still contemplating whether to challenge the decision by the Democratic Party's rules committee to split the Michigan delegates 69-59 in her favor. Each delegate would have a half vote. The agreement granted Obama 55 uncommitted Michigan delegates and four who would have been assigned to Clinton based on the state's results.
McAuliffe Sunday night called the panel's judgment "outrageous."
"People are angry," he said. "This does not unify our party, this crazy, cockamamie thing they came up with in Michigan."