Barack Obama secured another nomination victory overnight over Hillary Clinton ahead of more voting for US presidential nominations on Tuesday.
The victory in Maine means he is running close to Ms Clinton, who has a lead among super-delegates to the summer's Democratic nomination convention but is well behind the Illinois senator on State delegates.
Barack Obama on the campaign trail yesterday
Both candidates have estimated to have close to 1,100 delegates each, and they need 2,025 to win the nomination to contest November's presidential election.
"We have now won on the Atlantic coast, we've won on the north coast, we've won on the Pacific coast, and we've won in between those coasts," Mr Obama said after the Maine results were announced.
Ms Clinton sacked her campaign manager after losses in Louisiana, Nebraska, Washington and the Virgin Islands over the weekend.
The Clinton staff shake-up came before the "Potomac Primary" on Tuesday when both parties hold contests in the US capital and in neighbouring Maryland and Virginia.
Ms Clinton named Maggie Williams, a top aide when she was first lady to Bill Clinton, to take over as campaign manager from Patti Solis Doyle, who was moved into the role of senior adviser.
On the Republican side, John McCain is seen as clear favourite to take the Republican nomination despite losing weekend contests to his only serious rival, Mike Huckabee.
But the powerful conservative lobby are unhappy with Mr McCain as the Republican candidate, leaving open the outside possibility that Mr Huckabee, a Baptist preacher, could pull off a comeback.
The former Arkansas governor beat Mr McCain in Louisiana and Kansas on Saturday and ran a very close second in Washington state.
Agencies