Obama had a total of 2,068 delegates, including at least 14 from Puerto Rico. He also gained the support of two superdelegates during the day.
Clinton has 1,891.5, including at least 28 from Puerto Rico, with another 13 yet to be allocated from the day's primary.
There are 31 delegates combined at stake in Montana and South Dakota on Tuesday, and Obama's high command sounded confident that enough superdelegates were poised to quickly climb on and deliver him the nomination.
There have been numerous statements by party leaders in recent days indicating they favor a quick end to the presidential race so the party can begin unifying for the fall race against John McCain, the Arizona senator who wrapped up the Republican nomination months ago.
And while Clinton's campaign said it reserved the right to challenge the decision concerning Michigan's delegates, Speaker Nancy Pelosi rushed out a statement Saturday night that congratulated the committee "for its good work."
The California Democrat has been neutral in the race, but also has been calling uncommitted lawmakers in recent days, urging them to issue their own endorsements soon after Tuesday.
Robert Gibbs, a senior aide, did not rule out the possibility that Obama will seat the Michigan and Florida delegations at full strength if he is the nominee.
"I think any nominee may make some decisions at some point regarding those delegations," he said on ABC's "This Week."
Clinton's campaign chairman, Terry McAuliffe, appearing on the same program, declined to say what Clinton would do. "We'll see where we are when we finish up Tuesday," he said, "Then superdelegates will begin to move."
