US:Barack Obama will seek to build on the momentum of a string of weekend victories today when Virginia, Maryland and the District of Columbia hold primaries. Mr Obama has a comfortable poll lead over Hillary Clinton in all three states and his campaign events have drawn larger, more enthusiastic crowds.
Mrs Clinton has focused on Virginia, hoping for an upset victory but her campaign has lowered expectations in all three states. Maryland governor Martin O'Malley is supporting Mrs Clinton, but Virginia governor Tim Kaine and Washington DC mayor Adrian Fenty are backing Mr Obama.
Mr Obama won Maine's caucus on Sunday, following victories on Saturday in Washington state, Louisiana, Nebraska and the Virgin Islands.
Campaigning in Virginia, he warned that, even if Mrs Clinton won the presidency, she would be unable to win a majority big enough to effect real change.
"I think it is very hard for Senator Clinton to break out of the politics of the last 15 years and that politics is basically a politics where 47 per cent of the country is on one side, 47 per cent is on the other. You got 5 per cent in the middle, they all live in Florida and Ohio apparently. And so you battle it out and you never actually - even if you win - you don't have a working majority for change," he said.
Mr Obama pointed to the experience of former president Bill Clinton, arguing that his administration failed to achieve its policy goals because the electorate was too polarised.
"Keep in mind we had Bill Clinton as president when in 1994 we lost the house, we lost the senate, we lost governorships, we lost state houses. And so, regardless of what policies they wanted to promote, they didn't have a working majority to bring change about," Mr Obama said.
Mrs Clinton, who replaced her campaign manager this week, is looking forward to March 4th, when Ohio and Texas vote in primaries she is currently favoured to win. Her supporters fear, however, that Mr Obama's unbroken succession of victories in diverse states across the country could create a momentum that is hard to stop.
Mr Obama's huge financial advantage allows him to buy more advertising, open more offices and employ more staff in each state that votes between now and June 7th, when Puerto Rico holds the last primary of the nominating season.
On the Republican side, John McCain is confident of victory in Maryland and the District of Columbia, but he faces a strong challenge in Virginia from former Arkansas governor Mike Huckabee. Mr Huckabee has slowed Mr McCain's progress towards his party's nomination by claiming victories in Louisiana and Kansas over the weekend.
On the face of it, it is mathematically impossible for Mr Huckabee to win enough delegates to secure the nomination, but he has promised to remain in the race until Mr McCain secures the 1,191 he needs to win.
An Associated Press/Ipsos poll published yesterday showed Mr Obama with a slight lead over Mr McCain in a general election match-up, with Mrs Clinton level with the Republican senator.
Mr Obama led Mr McCain in the poll by 48 per cent to 42 per cent, while Mrs Clinton got 46 per cent to Mr McCain's 45 per cent.
Mr Obama added to his electoral victories on Sunday with a Grammy for the audio book of his Audacity of Hope and he was immortalised in wax yesterday at Madame Tussaud's in Washington. The waxwork shows Mr Obama standing behind the desk in the museum's replica of the Oval Office and flanked by wax figures of the Clintons and John F Kennedy and his wife Jacqueline.