WASHINGTON -- The basic rule of presidential primary politics - don't look back, look ahead - is in the middle of John McCain's cerebrum. It has yet to penetrate George W. Bush's cranium.
It accounts for the shift in McCain's emphasis - ''I'm a proud Ronald Reagan conservative'' - even as the details of his astonishing sweep in Michigan and Arizona were still pouring in. It also accounts for the renewed courtship of two pillars of the conservative establishment to whom California Republicans might listen carefully - moral scold Bill Bennett and Nancy Reagan. John Engler they're not.
McCain has a chance with Bennett, but virtually no chance at all with Nancy Reagan before March 7, the biggest voting moment in the history of primaries. The point is that McCain reveals an understanding of the challenge this poses and of the centrality of California in his quest.
Contrast that with Bush's behavior: No congratulatory phone call to McCain and his embarrassing attitude: I actually won the Republican primary in Michigan; only Democratic interlopers beat me, therefore once we get to Republican-only primaries, I can't lose.
The point is not that Bush is wrong. He's mostly right. Looking backward, the Michigan exit polling showed mirror images of Republicans (just 48 percent of the electorate who split 66-29 percent for Bush) and independents (35 percent of the total who split 67-26 for McCain. The margin among the Democrats (17 percent of the electorate and 8-1 for McCain) was decisive.
But looking to primaries ahead on the calendar, it is obvious that only sore losers ascribe this to mischief by eventual Al Gore voters. Focusing on the geography of the Michigan vote, Bush and McCain split in suburban Macomb County, birthplace of the so-called Reagan Democrats. More arresting was the fact that McCain held him to a slim win in the GOP stronghold of Kent County. And he matched Bush in the solidly GOP suburbs of Oakland County outside Detroit.
Going back to the exit polls, McCain showed an awesome ability to attract people who had never before voted in a Republican primary. The percentage in Michigan was 30, and his 2-1 margin among them was his margin of victory. This has direct applicability to California's sprawling landscape, despite the fact that only registered GOP votes will count in the winner-take-all contest for the state's 162 delegates.
There has already been a sizable increase in Republican registration in the weeks before the primary, and polls taken immediately after McCain's triumph in New Hampshire had him 20 points down and closing when Bush still had his aura of inevitability and none of his over-concentration on the GOP's right wing. Already, McCain is within polling margins of error in the second behemoth of March 7, New York, and sits more than pretty along the entire Atlantic Coast, from Maryland to Maine. In Ohio, moreover, he has every reason to launch a serious effort in a state that, like Michigan, allows independents and Democrats into its GOP primary.
McCain is convinced that the voting on March 7 will not be merely pivotal but will decide the nomination. What he means, top aides say, is that neither a political nor even a delegate arithmetic case can be made by the loser of both New York and California. And what that means is that McCain, befitting a guy who calls his effort a highwire act, accepts the challenge to win both.
Much more than the wooing of Bill Bennett and Nancy Reagan, what will count the most is McCain's success or failure in emphasizing the conservative aspects of his message and record, which he began doing even before the votes had been tallied Thursday evening. He is still inveighing against the ''Iron Triangle'' of campaign cash, lobbyists and legislation; he is still arguing that ''responsible adults'' support setting aside funds to shore up Social Security and Medicare and pay down the national debt.
But the Reagan conservative in him started talking about ''tearing up all 44,000 pages of the Internal Revenue code,'' above all the ones that benefit ''special interests.'' He also put new weight on his long history of violent opposition to government programs he disparages as pork-barrel. And, most notably, he offered a burst of what-I-represent phrases that included beefing up the military, protecting family values, cutting taxes his more moderate way, and ''protecting the unborn.''
The gamble is that this is more than enough conservatism for conservatives, and that supporting cuts in marginal income tax rates is no longer the only route to right-wing hearts. The gamble also is that the message isn't so hardline that moderate Republicans in closed primaries and independents in open ones will be turned off. It is a plausible approach by a guy who is now a plausible winner. Most important, it points ahead without looking back for momentum from Michigan.
The contrast with Bush is stark. He let McCain into the race over the weekend by campaigning as the front-runner still at his victory celebration in South Carolina. And today he's still dwelling on the past, denying that Michigan was anything more than another New Hampshire-sized bump in the road.
Thomas Oliphant is a Globe columnist.
