Washington: Democratic presidential front- runner Barack Obama picked up some fresh support, heading into a primary that could finally put him over the edge for the nomination after a grueling months-long battle against Hillary Rodham Clinton.

Obama, who has increasingly turned his attention to a general election showdown against Republican John McCain, got endorsements from three more superdelegates yesterday. Their backing is essential because they are free to vote as they chose in the party s nominating convention in August.

Heading into Sunday's primary in Puerto Rico, the first- term senator has a nearly insurmountable lead in delegates to the party's national nominating convention, and is now 45 short of the 2,026 needed to capture the party s White House nod.

Sunday's presidential primary, the island s first in nearly three decades, has brought the focus of American politics to a US territory where residents cannot vote in the general election and largely do not identify with any mainland party.

But, with 55 delegates to be apportioned between the two candidates, eyes are on the territory because Obama could theoretically clinch the nomination if he beats his rival. Clinton is counting on a victory to bolster her claim to have won the majority of popular votes based on a selective count of Democratic contests.

In the latest national Gallup Poll, Obama holds a 6-point lead nationally over Clinton, 50 per cent to 44 per cent.

Source : PTI