The president's own popularity is bottom-of-the-barrel low. Even allies privately fret that he's an albatross for the Republican looking to succeed him. Voters are crying out for change amid a prolonged Iraq war and a weakened economy.
But Bush also is beloved among GOP loyalists. He's a proven campaigner who can raise serious money. Those are huge assets as Arizona Sen. McCain works to rally the Republican base and fill his coffers while facing the Democrats' unrivaled enthusiasm and record-breaking fundraising.
The president and his would-be successor were appearing together Tuesday for the first time in nearly three months at an event that epitomized both elements of their tricky alliance - they were holding a fundraiser with GOP faithful at a private home, without the media to document it.
By the McCain campaign's own planning, the only time Bush and McCain would be captured on camera would be after the event - and too late to make most evening newscasts - on the Phoenix airport tarmac in the shadow of Air Force One, just before the president departs. McCain's fundraisers typically are closed to the press; the White House deferred to the campaign. No statements were expected.
Democratic opponent, an Illinois senator poised to become the Democratic nominee, got in a jab in advance.
"No cameras. No reporters. And we all know why. Senator McCain doesn't want to be seen, hat-in-hand, with the president whose failed policies he promises to continue for another four years," Obama chided while campaigning in Nevada. "But the question for the American people is: Do we want to continue George Bush's policies?"
Until recently, Obama's fundraisers have been closed to the press as well, reports CBS News' Maria Gavrilovic. Currently, the Obama campaign has a print pool reporter at all public fundraisers; however, cameras are not allowed.
For months now, Democrats have portrayed McCain as an extension of Bush. They have argued that McCain offers the same policies, despite his willingness to break with the Republican Party on a range of issues. And, they ran ads showing footage of Bush and McCain embracing each other in 2004, including one that said: "If all he offers is more of the same, is John McCain the right choice for America's future?"
Bush and McCain last appeared together publicly the day after the Arizona senator sewed up the nomination in early March.
The president welcomed the GOP's new standard-bearer to the White House at a brief Rose Garden news conference. It was a somewhat awkward scene. McCain fidgeted and said repeatedly that he'd welcome campaigning with Bush "in keeping with the president's heavy schedule." Bush, for his part, seemed eager to hand off the reins, saying the McCain would be making the hard decisions and "I'm going to be in Crawford with my feet up."
Mindful of the risks Bush brings, McCain has been aggressive about separating himself from the president. He has been laying out his own vision for the future with speeches on a slew of high-profile issues such as the U.S. posture in the world, climate change and the response to Hurricane Katrina.
During one such address Tuesday in Denver, McCain sought to contrast what he portrayed as a bipartisan vision on nuclear nonproliferation with that of Bush, who critics contend has engaged in partisan go-it-alone cowboy diplomacy that has strained U.S. relations across the globe.
In a way, even the White House is aiding in McCain's effort to chart his own course.
"President Bush isn't on the ticket," Dana Perino, the White House press secretary, said Tuesday in what has become a familiar refrain for characterizing Bush's campaigning on behalf of McCain. "At the end of the day, any candidate who's running for office has to stand on their own two feet. They have to chart a course for themselves. Every election is about change."
Still, a prideful White House has delicately tried to deal with McCain's not-so-subtle efforts to distance himself. When the president isn't by McCain's side, the White House offers lots of reasons: Bush is busy abroad, he's the commander in chief.
McCain has struggled to break from Bush on two key issues - the Iraq war and the economy. Both men support continued military involvement in Iraq, and they both seemingly back the same free-market economic principles. And that has given Democrats plenty to talk about.
To be sure, Bush seems aware that he could be a drag on McCain. In March, the president said: "If my showing up and endorsing him helps him - or if I'm against him and it helps him - either way, I want him to win."
Earlier this month, Bush seemed - by design or not - to assume the traditional lame-duck presidential role in trying to assist the GOP nominee-in-waiting.
In a speech to Israel's Knesset, Bush spoke of the president of Iran and warned against appeasing terrorists, which some interpreted as a slap at Obama, who has said he would be willing to meet with heads of state in places like Iran. Obama used Bush's remark to lump the president and McCain together.
McCain aides insist they had no advance knowledge of the president's remarks, and the White House publicly denied the comments were directed at Obama. Still, the episode underscored the pitfalls and benefits - as well as the evolution - of the Bush-McCain association.
In 2000, the two squared off in a bruising battle for the GOP nomination. Bush won but the scars for McCain lingered for a while, and, to this day, GOP operatives can be divided into Bush and McCain loyalists. In 2004, McCain embraced Bush, figuratively and literally, and campaigned on his behalf even as he railed against the president's Iraq policy and called for more troops.
Some two years later, as McCain launched his own White House bid, he found himself on the same page with Bush on Iraq as the president adopted his push for a troop build up. The two also were in agreement on the hot-button issue of eventual citizenship for millions of illegal immigrants in the country.
The combination led some of McCain's core supporters to worry that he was carrying Bush's water, and endangering his own presidential prospects in return.