[cnn-photo-caption image= http://i.l.cnn.net/cnn/2008/images/02/10/art.clinton.doyle.cnn.jpg caption="Patti Solis Doyle will now serve as senior adviser."](CNN) - Former Hillary Clinton chief of staff Maggie Williams will take over as campaign manager, Clinton staffers were told today. Current campaign manager and longtime friend Patti Solis Doyle will assume the role of senior adviser.
The switch has been rumored for more than a month – ever since Election Day in New Hampshire, when it was revealed that Williams would be joining the campaign in the wake of Clinton’s loss in the Iowa caucuses. At the time, Solis Doyle was urged to remain on board.
"I have been proud to manage this campaign, and prouder still to call Hillary my friend for more than sixteen years. I know that she will make a great president," Solis Doyle said in an e-mail to campaign staffers.
She added that the "the longest presidential campaign in the history of our nation" had "required enormous sacrifices from all of us and our families."
"...Maggie [Williams] is a remarkable person and I am confident that she will do a fabulous job."
A source close to Hillary Clinton tells CNN that Solis Doyle’s job had been at risk since Clinton's Iowa loss. Clinton's poor performance there coincided with the realization that the campaign had been running out of money – a fact which had not been related to the New York senator until then.
Still, Clinton stuck with Solis Doyle out of loyalty, says this source.
"There was a lot of dissatisfaction with the ground operation. There was nobody in charge,” another source tells CNN, adding that Solis Doyle was starting to lose the respect of some senior advisers, who fretted that campaign's message from state to state was not clear.
Doyle was "notorious for not returning phone calls which was starting to upset superdelegates and surrogates," and the endorsement process became "messy," says a source.
The New Hampshire win postponed the decision, but Solis Doyle failed to capitalize on the additional time. Maggie Williams began to take on many of the duties of campaign manager, and the lines of authority blurred.
The senior team was going to Williams for guidance, while the junior team was reporting to Doyle.
Insiders describe Doyle and Williams as close friends of Hillary Clinton. One said that "there didn't need to be a dual layer hostile environment - they just needed to sort it out."
Some in the campaign put a positive spin on the situation, saying that the move was anti-climactic – since Williams had effectively been in control for weeks – and would provide much-needed clarification. Clinton made the decision herself, said several sources, adding that there are not likely to be any hard feelings.
This week, Maggie Williams said she could not work with Solis Doyle, the source adds. It is unclear who, if anyone, might exit next: some in the campaign have said they would leave if Solis Doyle did.
In a statement released by her campaign Hillary Clinton said "I look forward to [Solis Doyle's] continued advice in the months ahead.
"Patti and I have worked with Maggie Williams for more than a decade. I am lucky to have Maggie on board and I know she will lead our campaign with great skill towards the nomination."Williams served as Hillary Clinton’s chief of staff during Bill Clinton’s first term.
(updated 6:20 p.m. ET with additional reporting)
–CNN's Jessica Yellin, Suzanne Malveaux and Sasha Johnson