McCain strategist keeps Obama vow, leaving campaign

FORT LAUDERDALE, Florida (Reuters) - A senior adviser to Republican presidential candidate John McCain said on Tuesday that he was stepping down to keep a commitment he made not to campaign against Democrat Barack Obama.

Mark McKinnon, who was in charge of the McCain campaign's advertising message, said he was still backing the Arizona senator, but that he was simply moving from active campaign participant to cheerleader.

"I'll still be around occasionally in my lucky hat," said McKinnon, who often wears a distinctive hat.

McKinnon, who was a key aide in President George W. Bush's two election victories, has expressed admiration for Obama and pledged not to campaign against the Democratic front-runner if he became the party's presidential nominee.

A McCain campaign official said McKinnon had notified the campaign of his decision to leave but declined further comment. The McCain campaign had been expecting McKinnon's move for some months and was not surprised at his decision.

Obama, an Illinois senator, remains locked in a battle with New York Sen. Hillary Clinton for the Democratic presidential nomination and the right to face McCain in the November general election.

Projections showed him losing the Kentucky primary to Clinton on Tuesday, but he was favored to win the later Oregon contest. His showing on Tuesday was expected to give him a majority of the elected delegates to the party's nominating convention in August.

Neither of the Democratic candidates have enough elected delegates to win the nomination, leaving the race to be decided by so-called superdelegates -- party leaders and elected officials who can vote for the candidate of their choosing.

The Cox News Service reported that McKinnon told McCain last summer that he would not work for him in the general election if Barack Obama became the Democratic nominee, saying

"I just don't want to work against an Obama candidacy."

At the time, Obama and McCain each looked like long shots for nomination.

On Sunday, McKinnon told the news service that he will continue to support McCain.

"I will still show up from time to time (and) talk to the candidate still, but not about Obama."

(Writing by JoAnne Allen; editing by David Alexander)