Washington - Senator Hillary Clinton claimed victory in the Indiana presidential primary even though most major US television networks had yet to project a winner late Tuesday in a race that has grown tighter throughout the night.

"Not too long ago my opponent made a prediction," she said of Senator Barack Obama. "He said I would win Pennsylvania, he would win North Carolina, and Indiana would be the tiebreaker."

"Well, tonight we've come from behind. We've broken the tie, and thanks to you it's full speed on to the White House," Clinton told a rally in Indianapolis, Indiana.

Obama had early congratulated the former first lady for her apparent victory in Indiana.

Clinton was clinging to a 52 to 48 per cent edge with 85 per cent of the votes counted, but some counties believed to favour Obama had yet to report final counts.

Clinton won the crucial state of Pennsylvania on April 22, and Obama handily defeated Clinton Tuesday in North Carolina. (dpa)