Clinton Campaign Manager Calls It Quits

Former First Lady's Chief of Staff to Take Over Running Presidential Race

Patti Solis Doyle announced that she is stepping down as the campaign manager for the presidential campaign of Sen. Hilary Clinton, D-N.Y., ABC News has learned that this afternoon.

In a note she sent to her staff, Solis Doyle announced that this week Maggie Williams, Clinton's chief of staff when she was first lady, "will begin to assume the duties of campaign manager." Solis Doyle, 42, said she would remain as a senior adviser to the campaign.

Solis Doyle, who has been with Clinton she was first lady of Arkansas, noted that "this has already been the longest Presidential campaign in the history of our nation, and one that has required enormous sacrifices from all of us and our families."

She wrote that she has 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."

The announcement came one day after Clinton's opponent, Sen. Barack Obama, D-Ill., swept four primary contests -- Nebraska, Washington state, Louisiana and the U.S. Virgin Islands -- and two days before the so-called "Potomac Primary" of Virginia, Maryland, and Washington, D.C., where Clinton's campaign says they do not expect her to fare well.

In a statement about Solis Doyle, Clinton said she was "enormously grateful for her friendship and her outstanding work" and said she "has done an extraordinary job in getting us to this point -- within reach of the nomination."

Of course, by now Clinton had expected to have secured the nomination. Clinton needs to win the Ohio and Texas contests next month, and Pennsylvania in April, and many in the campaign have more confidence that Williams will be better at ensuring those victories.

After Clinton lost the Iowa caucuses, Williams was brought in to help manage the campaign. Some campaign insiders say the move took power away from Solis Doyle.

Many on the campaign underline that family considerations also played a role in her decision. The mother of two young children, Solis Doyle is like many in the campaign who had expected the nomination fight to have been wrapped up one way or another by Feb. 5, Super Tuesday, and are exhausted and somewhat demoralized to think this struggle might last weeks or even months longer.

In an interview with ABC News' Kate Snow last Summer, Solis Doyle described the difficulty of balancing her family commitments -- she has a 6-year-old son and a 9-year-old daughter -- and her quite demanding job.

"I wake up my kids," she said. "I get them washed. I get them cleaned. I get them fed, you know? I get them ready for school. And then I begin my campaign day at 7:30 with conference call after conference call after conference call. And then, you know, by 9 o'clock, I'm in the office."

Solis Doyle said she would try to make it home for bath time, after which she would return to work online until 2 a.m. She would get up the next morning at 6 a.m.

A graduate of Northwestern University, Solis Doyle started out as Clinton's scheduler in Arkansas, and also served that role for her in the White House.

In 2000, Solis Doyle earned a leadership role in Camp Clinton after being sent from the White House to New York to help steer Clinton's senate campaign towards victory. The child of Mexican immigrants, Solis Doyle is fiercely loyal to Clinton.

Following is the e-mail she sent the campaign at 3:44 p.m. ET:

Over a year ago Hillary launched her campaign for President.

Her announcement began a historic effort that has inspired millions and brought hundreds of thousands to their feet all across this nation.

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.

This has already been the longest Presidential campaign in the history of our nation, and one that has required enormous sacrifices from all of us and our families.

During the last month I have been working closely with my longtime friend, Maggie Williams.

This week Maggie will begin to assume the duties of campaign manager. I will serve as a senior adviser to Hillary and the campaign and travel with Hillary from time to time on the road. Maggie is a remarkable person and I am confident that she will do a fabulous job.

Although I will continue to see you all at headquarters, I would be remiss if I didn't thank each of you for your dedication, excellence, and passion over the last year.

You are the best campaign staff in the history of Presidential politics and I am grateful to each of you for your hard work and friendship.

ABC News' Z. Byron Wolf and Eloise Harper contributed to this report.