When President Bush ventured here for a private fundraiser with John McCain on Tuesday night, his first real campaign appearance with the presumptive GOP nominee, the event was closed to the news media and their only joint public appearance was a photo op on the airport tarmac that lasted less than a minute.The same ground rules will cover Bush’s trip to Utah on Wednesday, where he will appear with former presidential candidate Mitt Romney to woo big-money Republican donors to McCain’s cause.The fleeting public appearances of an unpopular president on behalf of the potential heir to the leadership of the Republican Party underscore the delicate balance for McCain, who is trying to appeal to a restless GOP base that continues to embrace the president while reaching out to moderates and independents who want to move beyond the Bush administration. For now, the senator from Arizona remains locked in a tight race for the White House.From now until November, much of the presidential campaign will revolve around Democrats trying to equate a McCain victory with a third Bush term, and McCain trying to remain a breed apart.In the early stages of his general-election campaign, McCain is opting to avoid a sharp rupture with the White House. He has offered critiques of Bush on the response to Hurricane Katrina, global warming and the interrogation of terrorism suspects — and on Tuesday he presented a nuanced difference on nonproliferation policy — while backing Bush’s general approaches to Iraq, health care and tax policy. But as this week’s events make clear, McCain also plans to take advantage of Bush’s fundraising muscle to replenish his coffers.