Washington ? Democratic Sen. Hillary Rodham Clinton replaced campaign manager Patti Solis Doyle with longtime aide Maggie Williams on Sunday, engineering a shake-up in a presidential campaign struggling to overcome rival Sen. Barack Obama’s financial and political strengths.

The surprise announcement came hours after Obama’s sweep of three contests Saturday and shortly before the Illinois senator won caucuses in Maine on Sunday.

Determined to stem the tide, Clinton turned to a longtime confidante to manage her operations while the campaign acknowledged that she made a private visit to North Carolina this week to seek the endorsement of former rival John Edwards. Her rival Barack Obama was planning his own meeting today with Edwards, who confidantes said was torn over which candidate to back.

Campaign aides said Solis Doyle made the decision to leave on her own and was not urged to do so by the former first lady or any other senior member of the team.