Old Mr. Straight Talk has become so shaky a speaker that when he does talk straight, it's startling. On Wednesday night, John McCain mustered exactly one such moment of clarity: "Senator Obama, I am not President Bush. If you wanted to run against President Bush, you should have run four years ago."

    Thanks largely to this line, McCain's remaining base in the political press graded his last debate performance his best. The public, not so much. As with the previous debates, every poll found Barack Obama the winner, this time by as much as two-to-one ratios. Obama even swept the focus group convened by the G.O.P. pollster Frank Luntz in the once-impregnable McCain bunker of Fox News.

    Perhaps voters were unimpressed by McCain's big moment because they can figure out the obvious rejoinder: Why didn't McCain run against President Bush four years ago - as he had four years before that? Instead McCain campaigned for Bush's re-election, cheered for Bush policies he once opposed and helped lower himself and America into the pit where we find ourselves today.

    The day after the debate, McCain put up a new ad trying yet again to shake the president. "The last eight years haven't worked very well, have they?" he asks, as if he were an innocent bystander the entire time. But no matter what McCain says or does, he still can't quit the guy. Heading from a Midtown hotel to a fund-raiser the night before facing Obama onstage on Long Island last week, the McCain motorcade lined up right next to the New York red-carpet premiere of Oliver Stone's "W." A black cat would have been a better omen.

    The election isn't over, but there remain only three discernible, if highly unlikely, paths to a McCain victory. A theoretically mammoth wave of racism, incessantly anticipated by the press, could materialize in voting booths on Nov. 4. Or newly registered young and black voters could fail to show up. Or McCain could at long last make good on his most persistent promise: follow Osama bin Laden to the gates of hell and, once there, strangle him with his own bare hands on "Hannity & Colmes."

    Even Republicans are rapidly bailing on a McCain resuscitation. It's a metaphor for the party's collapse that on the day of the final debate both Nancy Reagan and Dick Cheney checked into hospitals. Conservatives have already moved past denial to anger on the Kubler-Ross scale of grief. They are not waiting for votes to be counted before carrying out their first round of Stalinist purges. William F. Buckley's son Christopher was banished from National Review for endorsing Obama. Next thing you know, there will be a fatwa on that McCain-bashing lefty, George Will.

    As the G.O.P.'s long night of the long knives begins, myths are already setting in among the right's storm troops and the punditocracy alike as to what went wrong. And chief among them are the twin curses of Bush and the "headwinds" of the economy. No Republican can win if the party's incumbent president is less popular than dirt, we keep being told, or if a looming Great Depression 2 is Issue No. 1.

    This is an excuse, not an explanation. It absolves McCain of much of the blame and denies Obama much of the credit for their campaigns. It arouses pity for McCain when he deserves none. It rewrites history.

    Bush's impact on the next Republican presidential candidate did not have to be so devastating. McCain isn't, as he and his defenders keep protesting, a passive martyr to a catastrophic administration. He could have made separating himself from Bush the brave, central and even conservative focus of his campaign. Far from doing that, he embraced the Bush ethos - if not the incredible shrinking man himself - more tightly than ever. The candidate who believes in "country first" decided to put himself first and sell out his principles. That ignoble decision is what accounts for both the McCain campaign's failures and its sleaze. It's a decision McCain made on his own and for which he has yet to assume responsibility.

    Though it seems a distant memory now, McCain was a maverick once. He did defy Bush on serious matters including torture, climate change and the over-the-top tax cuts that bankrupted a government at war and led to the largest income inequality in America since the 1930s. But it isn't just his flip-flopping on some of these and other issues that turned him into a Bush acolyte. The full measure of McCain's betrayal of his own integrity cannot even be found in that Senate voting record - 90 percent in lockstep with the president - that Obama keeps throwing in his face.

    The Bushian ethos that McCain embraced, as codified by Karl Rove, is larger than any particular vote or policy. Indeed, by definition that ethos is opposed to the entire idea of policy. The whole point of the Bush-Rove way of doing business is that principles, coherent governance and even ideology must always be sacrificed for political expediency, no matter the cost to the public good.

    Like McCain now, Bush campaigned in 2000 as a practical problem-solver who could "work across the partisan divide," as he put it in his first debate with Al Gore. He had no strong views on any domestic or foreign issue, except taxes and education. Only after he entered the White House did we learn his sole passion: getting and keeping power. That imperative, not the country, would always come first.

    One journalist who detected this modus operandi early was Ron Suskind, who, writing for Esquire in January 2003, induced John DiIulio, the disillusioned chief of the White House Office of Faith-Based and Community Initiatives, to tell all. "There is no precedent in any modern White House for what is going on in this one: a complete lack of a policy apparatus," DiIulio said. "What you've got is everything - and I mean everything - being run by the political arm. It's the reign of the Mayberry Machiavellis."

    If politics strongarm everything, you end up with the rampant cronyism, nonexistent long-term planning and abrupt, partisan policy improvisations that fed the calamities of Iraq, Katrina and the economic meltdown. Incredibly, McCain has nakedly endorsed the Bush-Rove brand of governance in his own campaign by assembling his personal set of lobbyist cronies and Rove operatives to run it. They have not only entangled him in a welter of conflicts of interest, but they've furthered cynical political stunts like the elevation of Sarah Palin. At least Bush and Rove didn't try to put an unqualified hack like, say, Alberto Gonzales half a heartbeat away from the presidency.

    As if the Palin pick weren't damning enough, McCain and his team responded to the financial panic by offering their own panicky simulation of the Bush style of crisis management in real time. Fire the S.E.C. chairman and replace him with Andrew Cuomo! Convene a 9/11 commission to save Wall Street! Don't bail out A.I.G.! Do bail out A.I.G.! Reacting to polls and the short-term dictates of 24-hour news cycles, McCain offered as many economic-policy reboots in a month as Bush offered "Plans for Victory" during the first three years of the Iraq war.

    Now McCain is trying to distract us from his humiliating managerial ineptitude by cranking up the politics of fear - another trademark Bush-Rove strategy. But the McCain camp's quixotic effort to turn an "old washed-up terrorist" into a wedge issue as divisive as same-sex marriage is too little, too late and too tone-deaf at a time when Americans are suffering too much to indulge in 1960s culture wars. Voters want policies that might actually work rather than another pandering, cynical leader who operates mainly on the basis of his "gut" and political self-interest.

    The former Bush speechwriter David Frum has facetiously written that McCain could be rescued by "a 5,000-point rise in the Dow and a 20 percent jump in home prices." But the economy, stupid, can't be blamed for McCain's own failures, any more than Bush can be. Even before the housing bubble burst and Wall Street tumbled, voters could see that the seething, impulsive nominee isn't temperamentally fit to be president.

    That's where the debates have come in. There may have been none of those knockout blows the press craves, but the accretional effect has been to teach the public that McCain isn't steady enough to run the country even if the economy were sound, and that Obama just might be.

    In Debate No. 1, you could put the volume on mute and see what has proved to be the lasting impressions of both candidates start to firm up. In Debate No. 2, McCain set the concrete: he re-enacted the troubling psychological cartography of his campaign "suspension" by wandering around the stage like a half-dotty uncle vainly trying to flee his caregiver. After the sneering and eye-rolling of McCain's "best" debate on Wednesday, CNN's poll found the ever-serene Obama swamping him on "likeability," 70 to 22 percent.

    At least McCain had half a point on Wednesday night when he said, "I am not President Bush." What he has offered his country this year is an older, crankier, more unsteady version of Bush. Tragically, he can no sooner escape our despised president than he can escape himself.