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Nine News: Robert Shortt, Washington Correspondent, reports that Hillary Clinton is trailing Barack Obama as they enter primaries in Montana and South Dakota
Senator Hillary Clinton has said her fight for the US Democratic presidential nomination will go on after she won a largely symbolic victory in Puerto Rico.
Her campaign earlier suffered a setback when the party compromised over contest results from Florida and Michigan.
The final two Democratic nominating contests - Montana and South Dakota - will be held on Tuesday.
