Washington, Feb 11: Senator Hillary Rodham Clinton has replaced her campaign manger, Patti Solis Doyle.

Clinton’s long time aide Maggie Williams is the new manager.

The move to replace Doyle was taken after Democratic presidential rival Barack Obama defeated Clinton in four key primary contests over the weekend.

Obama, aiming to become the first black US President in history, garnered roughly twice the votes received by Clinton in Nebraska, Washington and Louisiana caucuses and nearly 90 per cent of the total ballots in Virgin Islands, slicing into the slender lead of the former first lady as he grabbed a majority of the 161 delegates at stake.

Clinton, bidding to create history by becoming the first woman President of the United States, has 1095 delegates against Obama's 1070.

Republican John McCainn on the other hand suffered two embarrassing defeats after almost sealing his nomination in the 'Super Tuesday' vote.

Both Clinton and Obama are preparing for Tuesday primaries in Maryland, Virginia and Washington DC, which account for nearly 200 delegates.

A total of 2,025 delegates are required to win the Democratic nomination at the party's National Convention for the November Presidential polls.

"We won north, we won south, we won in between," Obama, 46, locked in a neck-and-neck fight with Clinton for weeks, told cheering supporters in Richmond, Virginia.

Obama said the election is now a choice between "who has the most experience in Washington, or debating him about who's most likely to change Washington. Because that's a debate we can win."

Indications are that the Illinois Democrat will have a good night on Tuesday as well. (ANI)