White House hopeful Hillary Clinton said on Sunday she has replaced her campaign manager with a long-time aide as she fights a tight race with Barack Obama for the Democratic presidential nomination.
Maggie Williams, a top aide to Clinton when her husband Bill Clinton was president, has taken over from Patti Solis Doyle as campaign manager.
Aides to Clinton, a New York senator who would be the first woman president, played down any notion that the staff change was a signal of trouble for her campaign.
Solis Doyle will move into the role of senior adviser to Clinton during the remaining state-by-state races for the Democratic nomination to contest the presidential election in November.
"Patti Solis Doyle has done an extraordinary job in getting us to this point," Clinton said in a statement. "I'm lucky to have Maggie on board and I know she will lead our campaign with great skill towards the nomination."
Clinton did not spell out why Solis Doyle was being replaced. The move comes as Obama, an Illinois senator, has picked up momentum in the race, raking in millions in campaign contributions and scoring wins in three states on Saturday.
"This has been the longest primary campaign in history. It was an appropriate time to make a switch," said Doug Hattaway, a spokesman for the Clinton campaign, adding that the move did not reflect any change in the candidate's overall strategy.
Clinton and Obama, who would be the first black president, are about even in pledged delegates but both are well short of the 2,025 needed to win the Democratic nomination.
Democrats held a nominating race in Maine on Sunday but the next big voting day comes on Tuesday, when Democrats and Republicans have contests in Washington, DC, and neighbouring states Virginia and Maryland.
Obama was running ahead in opinion polls and was expected to do well in the Tuesday balloting.
(Editing by John O'Callaghan and Philip Barbara)