When I interviewed her in June, Valerie Jarrett, who will join Barack Obama's campaign as an part-time senior adviser, told me that, by the late fall, she would be, more or less, working on her best friend's behalf on a day-to-day basis.

Jarrett, a former deputy chief of staff to Chicago mayor Richard Daley, has known the Obama family for more than a decade. She runs Habitat LLC, a Chicago real estate company, and may one day run for mayor. A lifelong Chicagoan, she will be the campaign's outsider-in-chief, complementing the bevy of seasoned political insiders who now run Obama's campaign.

Obama advisers insisted that Jarrett's expanded role should not be read as a sign that Obama has lost confidence in campaign director David Plouffe.

But it's also true that Obama and his wife Michelle decided to bring Jarrett inside the campaign a little earlier than some in Obama's world had anticipated. The Obamas were responding to suggestions from friends outside the campaign who thought the campaign could use a firmer managerial hand.

One Democrat close to Obama said that the candidate agreed that the "nuts and bolts" of the campaign needed to be "tightened." But the Democrat said that Obama had "complete confidence" in Plouffe as a planner and a strategist and was worried that press accounts of any change would falsely incorporate the assumption that Plouffe was somehow being demoted.

The demands on Plouffe's time are extensive; donors and major political figures line up to meet with him, and the addition of high-level talent -- staffers and friends who have stature and the ear of Obama -- will allow Plouffe more time to run the campaign.

Plouffe is among the newer members of Obama's inner circle. He has hiring and firing authority and oversees the campaign's budget along with Marty Nesbitt, a Chicago entrepeneur who is also Obama's best friend. Nesbitt serves as campaign treasurer.

Jarrett will serve as a consigliere of sorts who can mediate disputes between senior staff members and make sure that major projects are completed to Obama’s standards. She will be, for a campaign dealing with challenging questions about race, its most influential African American.

Another change: strategist Steve Hildebrand will take a more aggressive role in running the campaign's political and field departments. Hildebrand put together those departments, wrote most of the campaign's field plan, and divides his time between the campaign's Chicago headquarters and its field offices in Iowa, New Hampshire, Nevada and South Carolina.

For a major presidential campaign, Obama's inner circle has been relatively free of the acrimony that generally results from the combination of healthy egos and high-pressure decisions. David Axelrod has been the chief strategist, responsible for crafting Obama's campaign argument. Robert Gibbs is the guardian of Obama's image. Pete Rouse, Obama's Senate chief of staff, is a veteran of Capitol Hill politics.

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