McCain Shakes Up Campaign Again

John McCain's campaign manager and top adviser, along with two other top aides, have left the Republican's ailing presidential campaign, one week after reporting second-quarter fundraising that came in far below expectations.

For the one-time Republican front-runner, an old blues song summed it up: "If it weren't for bad news, there'd be no news at all."

At the very moment McCain was laying out his case for perseverance in Iraq, reports CBS News political correspondent Jeff Greenfield, two top campaign aides, manager Terry Nelson and chief strategist John Weaver, announced they were leaving the campaign immediately, a result of staff tensions fueled by campaign cash woes.

"It has been a tremendous honor to serve Senator McCain and work on his campaign," Nelson said. "I believe John McCain is the most experienced and prepared candidate to represent the Republican Party and defeat the Democratic nominee next year."

One official said Nelson resigned as campaign manager for the Republican presidential candidate and Weaver stepped down from his post of chief strategist on Tuesday. Other officials said Nelson was fired, but several people close to Nelson disputed that characterization.

Following the two out the door were political director Rob Jesmer and deputy campaign manager Reed Galen, officials said.

Nelson had previously worked for President Bush's 2004 re-election campaign while Weaver has been a longtime friend and adviser to the Arizona senator. In a statement, McCain said he accepted both their resignations with "regret and deep gratitude."

"In the days and weeks ahead this campaign will move forward, and I will continue to address the issues of greatest concern to the American people, laying out my vision for a secure and prosperous America," McCain said.

McCain hired Nelson more than a year ago to start laying the foundation for the senator's long-expected second presidential run. Weaver has been with McCain for at least 10 years.

Two officials said Rick Davis, a longtime aide to McCain, will take over the campaign. One McCain aide told CBS News that Mark Salter, a longtime adviser known as McCain's alter-ego after helping the senator write several books, was staying with the campaign on a pro bono basis.

As word of the changes became public, McCain was on the Senate floor defending the troop buildup in Iraq and contending that reinforcements had only just been put in place. He made his sixth trip to Iraq last week.

"Make no mistake. Violence in Baghdad remains at unacceptably high levels," but the United States and Iraq seem to be "moving in the right direction," McCain said. "The progress our military has made should encourage us."

At the Capitol, McCain said he would "of course" remain in the presidential race, and disputed the idea that the staff changes marked a major shakeup that reflects his campaign's recent troubles.

"People are free to make their own assessments. I think we're doing fine," McCain said. "I'm very happy with the campaign the way it is."

The shakeup is only the latest change made to boost McCain's presidential hopes, which have fallen precipitously since early this year, when he was seen as the Republican front-runner and the choice of the party's establishment. Since then, he has reported lackluster fundraising in two consecutive quarters and seen his poll numbers fall, both nationally and in key early-voting states, especially after McCain stuck by a failed immigration bill that incensed much of the conservative Republican voting base.

Last week, Nelson announced he would decline a salary to help the campaign save money after reporting that it had raised $11.2 million in the second quarter of 2007, placing him behind both Rudy Giuliani and Mitt Romney. McCain also reporting having only $2 million on hand. The announcment was followed by cutbacks in staff salaries and layoffs throughout McCain's organization.

The campaign is still considering accepting federal matching funds for the campaign, even though that would subject McCain to spending restrictions that would not apply to his opponents.

Earlier this year, McCain said he would not compete in this August's straw poll in Ames, Iowa, which is usually seen as a key barometer of who is leading the Republican field. Romney is the only top-tier Republican candidate committed to the poll.

McCain's woes come as former Sen. Fred Thompson of Tennessee is about to enter the race. Thompson is expected to strongly compete for the support of the conservative voters McCain and Romney have been courting.