The Associated Press-Ipsos poll released on Monday showed a significant swing to Mrs Clinton among independents, young people and seniors who - with her working-class Democratic base - propelled her to a nearly 10 percentage-point victory last week in the Pennsylvania primary.

With that newfound support, Mrs Clinton gained ground this month in the hypothetical match with Mr McCain, the Republican nominee-in-waiting, and now leads him 50 per cent to 41 per cent.

Mr Obama remains virtually tied with Mr McCain, 46 per cent to 44 per cent.

Both Democrats were roughly even with Mr McCain in the previous poll about three weeks ago.

Both Mr Obama and Mrs Clinton campaigned in North Carolina on Monday, pushing supporters to go to the polls early in the southern state and in Indiana before both states hold primaries on May 6. He is favoured in North Carolina while the two are competing closely in Indiana.

Mrs Clinton picked up a prized endorsement - North Carolina Governor Mike Easley was expected to announce his support for the former first lady on Tuesday morning in Raleigh, the state capital.

Mr Easley is a Democratic superdelegate, one of the nearly 800 party and elected officials who are free to vote for either candidate regardless of state primary and caucus results.

The endorsement compounded a bad day for Obama that began with an unrepentant Rev Jeremiah Wright - his former pastor - returning to public view, slamming US foreign policy and treatment of African Americans.

Chief Obama strategist David Axelrod told NBC that Rev Wright's recent string of public appearances were a 'needless distraction'. Mr Obama said Rev Wright does not speak for his campaign. - AP