The Illinois senator told Democrat voters heading to the polls today in Indiana and North Carolina: "I need help."

With less than a month to go before the state-by-state vote ends, the Obama camp is desperate to finish off Mrs Clinton's campaign to become the Democrat's presidential nominee.

Mr Obama, 46, also broke a fragile truce with the former first lady yesterday to attack her threat to "totally obliterate" Iran.

Claiming it was "the kind of cowboy diplomacy, or lack of diplomacy, we've seen out of George Bush", he also lambasted the New York senator's "sabre rattling" and her "phony ideas" on issues including health and fuel prices.

His comments came as Tom Hanks publicly pledged his support for Mr Obama, who is hoping to become America's first black president.