Top two aides quit McCain's 2008 campaign

By John Whitesides, Political Correspondent

WASHINGTON (Reuters) - Republican John McCain's top two aides left his struggling U.S. presidential campaign on Tuesday, dealing a sharp blow to the Arizona senator and casting doubt on the future of his 2008 bid.

McCain said he would continue his White House run despite the departures of manager Terry Nelson and longtime chief strategist John Weaver, which were announced as McCain took the Senate floor to defend President George W. Bush's strategy in Iraq.

Once a front-runner in the Republican field, McCain has fallen behind as his staunch backing for Bush on the unpopular Iraq war and on an overhaul of immigration laws cost him support among both moderates and conservatives.

"We've had ups and downs in other campaigns and we'll have ups and downs with this campaign. I'm very happy with where we are," McCain told a crush of reporters at the Capitol, promising to "out-campaign" his rivals.

Nelson was Bush's political director during his 2004 re-election campaign and Weaver was McCain's top strategist during his unsuccessful 2000 race for the White House. In statements released by the campaign, neither man offered a reason for leaving.

"I believe John McCain is the most experienced and prepared candidate to represent the Republican Party and defeat the Democratic nominee next year," Nelson said.

Rick Davis, McCain's campaign manager in 2000 and chief executive officer of this campaign, will take over managing McCain's White House run.

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