SAN JUAN, Puerto Rico — Senator Clinton won a lopsided, but largely symbolic victory today in Puerto Rico’s presidential primary, the final act in a weekend of tumult that brought Senator Obama tantalizingly close to the Democratic presidential nomination.

The former first lady was gaining more than 60% of the vote in early returns, and a pre-election poll suggested she could wind up with nearly two-thirds support.

In defeat, Mr. Obama was on track to gain at least 14 delegates, bringing him within 50 of the 2,118 needed for the nomination.

Aides predicted he could clinch the nomination as early as this week, when Montana and South Dakota close out the primary season, and he said he was confident the party would unite for the fall campaign. “First of all, Senator Clinton is an outstanding public servant, she has worked tirelessly during this campaign … and she is going to be a great asset when we go into November,” he told an audience at Mitchell, S.D. “Whatever differences Senator Clinton and I may have, those differences pale in comparison to the other side.”

Mr. Obama’s confidence in the outcome of the historic battle for the nomination reflected the outcome of yesterday’s meeting of the Democratic Party’s rules and bylaws committee. Before an audience that jeered and cheered by turns, the panel voted to seat disputed delegations from Michigan and Florida, but give each delegate only one-half vote rather than the full vote sought by the Clinton campaign.

While the decision narrowed the gap between Mrs. Clinton and Mr. Obama, it also erased the former first lady’s last, best chance to change the course of the campaign.

A telephone poll of likely Puerto Rican voters taken in the days leading up to the primary showed an electorate sympathetic to Mrs. Clinton — heavily Hispanic, as well as lower income, and more than 50% female. About one-half also described themselves as conservative.

Nearly three-quarters of all those interviewed said they had a favorable view of Mrs. Clinton, compared to 53% for Mr. Obama. One-third said they didn’t know enough about Mr. Obama to form an impression.

The survey was conducted Tuesday through yesterday for The Associated Press and the television networks by Princeton Survey Research Associates International. It included 1,587 likely voters with a candidate preference; sampling error was plus or minus 3.1%.

With 29% of the precincts reporting, the Puerto Rico vote count showed Mrs. Clinton with 53,451 votes, or 68%, to Obama’s 25,593 votes, or 32%.

Mr. Obama had a total of 2,068 delegates in The Associated Press count, including at least 14 from Puerto Rico. He also gained the support of two superdelegates during the day.

Mrs. Clinton has 1,891.5, including at least 28 from Puerto Rico, with another 13 yet to be allocated from the day’s primary.

Mr. Obama campaigned in South Dakota during the day, while Mrs. Clinton was in Puerto Rico hoping for a victory celebration.

There are 31 delegates combined at stake in Montana and South Dakota on Tuesday, and Mr. 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 Senator McCain of Arizona, who wrapped up the Republican nomination months ago.

And while Mrs. Clinton’s campaign said it reserved the right to challenge the decision concerning Michigan’s delegates, Speaker Pelosi rushed out a statement last 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.

Mr. Gibbs also did not rule out the possibility that Mr. 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.”

Mr. McAuliffe, appearing on the same program, declined to say what Mrs. Clinton would do. “We’ll see where we are when we finish up Tuesday,” he said. “Then superdelegates will begin to move.”

He, as well as Mrs. Clinton’s communications director, Howard Wolfson, said the former first lady had won more votes than Mr. Obama in the course of the primary campaign.

Mr. Gibbs disputed that — and Mrs. Clinton’s claim includes estimates for caucuses in Iowa, Nevada, Maine, and Washington state, where no official candidate popular vote is available. It also includes the results from Florida, where no campaigning occurred, as well as Michigan, where Mr. Obama did not receive any votes because his name was not on the ballot.

Mrs. Clinton’s campaign objected to the rules committee decision on Michigan’s delegates, saying it had arbitrarily taken four delegates away from the former first lady and awarded them to Obama. As a result, officials said she may seek a decision on the issue by the convention credentials committee, which meets shortly before the convention opens in Denver.

A top adviser to Mrs. Clinton, Harold Ickes, said on NBC’s “Meet The Press” no decision had yet been made.

“I have not had a chance to talk with Senator Clinton at any length about it, and obviously this will be a big decision. But her rights are reserved,” he said.

But one of her strongest supporters, Governor Rendell of Pennsylvania, sounded uninterested in a further challenge.

“I don’t think we’re going to fight this at the convention, because even were we to win it, unless it’s going to change enough delegates for Senator Clinton to win the nomination, then it would be a fight that would have no purpose,” Mr. Rendell said on CBS’ “Face the Nation.”