Nashua, New Hampshire: A new opinion poll showed Barack Obama jumping to a significant lead ahead of Tuesday's New Hampshire primary.

A USA Today/Gallup poll said Obama had opened up a 13-point lead over rival Hillary Clinton in New Hampshire, 41 per cent to 28 per cent, to 19 per cent for former North Carolina Senator John Edwards.

Obama, an Illinois senator seeking to be the first black US president, built on his victory in Iowa last week with a significant bounce in New Hampshire.

In the hotly contested Republican race, Arizona Senator John McCain leaped ahead of former Massachusetts Governor Mitt Romney even as Romney tried to raise doubts about McCain.

New Hampshire's primary is the next battleground in the state-by-state process of choosing Republican and Democratic candidates for November's election to replace President George W. Bush.