His management of his campaign offers a glimpse of how he might run the White House. He would, it appears, be a president who is intensely interested in issues (particularly foreign affairs) and open to conflicting opinions, but also impetuous at times and tolerant of the kind of internal churning that can impede orderly decision-making and keep aides on edge.

While President Bush has been criticized for being too insular and too slow to adapt to changing circumstances, Mr. McCain’s leadership of his campaign suggests a less hierarchical, more free-form style, much closer to that of President Bill Clinton.

For now, Mr. McCain’s executive style looms as a potential obstacle to his hopes of getting to the White House. His campaign has been rocked by personnel changes and often well-publicized differences. And for all the efforts to maintain discipline, he continues to be plagued by misstatements and apparent gaffes as he at times bucks what his own campaign is trying to do. After his campaign spent days mocking Mr. Obama for suggesting that proper tire pressure was one way of conserving fuel, Mr. McCain undercut the message, stating : “Senator Obama a couple of days ago said that we ought to all inflate our tires, and I don’t disagree with that. The American Automobile Association strongly recommends it.”

As Mr. Obama’s campaign pounced on the remark, the McCain campaign quickly sent out an e-mail message to reporters noting that Mr. McCain had gone on to say that he did not believe that would lead to energy independence.

By all accounts, the most recent shake-up of his campaign has helped. It put Steve Schmidt  known for a tough management style and who made clear he would leave if he was not given the authority to impose discipline  in a senior role at headquarters, working alongside Rick Davis, a longtime survivor of the McCain staff wars.

Mr. Schmidt has sought to cut down on Mr. McCain’s use of his cellphone and limit the people who have regular access to Mr. McCain in an effort to keep him more focused, advisers said. He has been the impetus for an effort by Mr. McCain to limit sharply his engagements with reporters, the kind of freewheeling encounters that Mr. McCain enjoys  and that helped him charm the news media for years  but that often lead him to veer from his campaign’s message of the day.

There are 8 a.m. calls every day in which the campaign settles on the daily message or attack. Someone in Mr. McCain’s entourage  typically Nicolle Wallace, a Schmidt ally and a veteran of Mr. Bush’s 2004 campaign and White House who recently joined the campaign as a traveling senior adviser  is given the responsibility of making sure Mr. McCain agrees to the message and tries to stick to it.