Presidential hopeful Barack Obama completed a weekend whitewash over Democratic rival Hillary Clinton by winning the Maine caucuses to sweep all five contests during the last two days.

According to unofficial tallies, Obama secured nearly 60 per cent of votes in the state, which has 34 delegates for the party's national convention in Denver, while Clinton managed just 40 per cent.

The win capped an amazing weekend for the first-time senator, who also won in Nebraska, Washington, Louisiana and the US Virgin Islands on Saturday.

The shocking setback to Senator Clinton has sent her campaign scrambling for answers, and the first casualty was her campaign manager, Patti Solis Doyle, who has been replaced by the former first lady's long-time aide, Maggie Williams.

Obama is expected to gain further momentum in his bid to become the first black US president in history by the time Tuesday's 'Beltway' primaries in Maryland, Washington DC and Virginia are over.

Obama is is expected to win handsomely in Maryland and Washington DC, and he is also seen as leading in Virginia.

With the Beltway primaries not expected to go Clinton's way, analysts feel the New York Senator must win in the big ticket states of Ohio and Texas in the beginning of March to keep her campaign's momentum going for another big contest in Pennsylvania.

Campaigning in Alexandria, Virginia, Obama said Clinton was a 'capable person' but people see her as part of a divisive political era.

"I think it is very hard for Senator Clinton to break out of the politics of the past 15 years," Obama said.
 
"Senator Clinton starts off with 47 per cent of the country against her...That's a hard place to start," he said.

Image: Illinois Senator Barack Obama addresses supporters at a rally in Alexandria, Virginia.
Reportage: PTI | Photograph: Saul Loeb/AFP/Getty Images