After weekend strategy meetings at McCain's Arizona ranch, advisers said coordinating the campaign with the White House remains unresolved until McCain wins enough delegates to be GOP presidential nominee, The New York Times reported Monday.

Advisers must figure out how to use Bush enough to woo the conservative wing still leery of McCain but not so much that independents and moderate Democrats abandon him.

Democratic presidential candidates Sens. Hillary Clinton of New York and Barack Obama of Illinois link McCain to Bush, telling audiences that a McCain presidency would mean extending Bush's policies.

McCain's advisers insist they are reluctant to have a sitting president campaign with McCain. They have precedent: President Ronald Reagan rarely appeared beside former President George H.W. Bush, the current president's father, when he campaigned.

"What an incumbent president can do is help a new nominee with fundraisers, maybe with unifying the party and maybe with getting out the vote in Republican areas," Charles Black, a McCain adviser who has been part of Republican presidential campaigns since 1976, told the Times.