Obama's confidence in the outcome of the historic battle for the nomination reflected the outcome of Saturday'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 Clinton and Obama, it also erased the former first lady's last, best chance to change the course of the campaign.

With 57 percent of the precincts reporting, the Puerto Rico vote count showed Clinton with 131,304 votes, or 68 percent, to Obama's 61,614 votes, or 32 percent.

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

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

The survey was conducted Tuesday through Saturday by Princeton Survey Research Associates International. It included 1,587 likely voters with a candidate preference; sampling error was plus or minus 3.1 percentage points.

A child holds a poster in support of US Democratic presidential candidate Sen. Hillary Clinton during a campaign rally through Bayamon, Puerto Rico, May 31, 2008. [Agencies]