Sen. John McCain, R-Ariz., endured boos amid the applause when he spoke at last week's Conservative Political Action Conference. Good for him. And good for the Republicans. Those boos may not have been music to McCain's ears, but they were one indication that he is the healthiest thing to happen to the Republican Party since Ronald Reagan.

This year's primary season has been so full of healthy developments that you could package it with oat bran and hawk it at Whole Foods. The country can thank its lucky stars that the process has pushed forward—in McCain and in Democratic Sens. Hillary Rodham Clinton and Barack Obama—the three most formidable figures in American politics. If Obama wins the Democratic nomination, the result will pit the two most widely admired political figures of their generations against each other in a presidential race. The last time the country saw anything remotely like that was when Dwight Eisenhower faced Adlai Stevenson in 1952 and 1956.

Democrats can be grateful they have two tough races on their hands, first for the nomination and then, as now seems virtually certain, against McCain in the general election. Remember LBJ and Jimmy Carter? When Democrats win against weak opponents or crippled parties, they overreach, underperform, and lose touch with the country.

But the healthiest news of all is McCain's emergence as the presumptive Republican nominee. Of all the Republicans in America, McCain is best positioned to undo the errors and correct the excesses of Bush-era Republicanism. If the Bush years were snakebit, think of McCain as an antivenin.

Not all Republicans see it that way, of course. Some would like to see more ruthless partisanship, more fiscal recklessness, more polarization, more presidential monarchism, more erosion of U.S. credibility on human rights, more immigration-bashing. Wiser Republicans, though, know better. They understand that the Big Four of post-Reagan, post-Gingrich Republicanism—President Bush, Vice President Cheney, former White House strategist Karl Rove, and former House Majority Leader Tom DeLay—steered the party to a dead end.

Wise Republicans know, to begin with, that the party is lost if it cannot rebuild its own center and appeal to the country's. Bush-era Republicanism was all about suppressing the center and mobilizing the extremes, on the (correct) assumption that conservatives outnumber liberals. It worked, for a while, because of 9/11 and because the Democrats unwittingly cooperated. Forced to choose between the Republican Right and the Democratic Left, independents leaned Republican or just stayed home.

Unfortunately for Republicans, the Democrats wised up and started choosing candidates with centrist appeal. Forced to govern from the center of their party instead of the center of the country, Republicans meanwhile swung too far to the right. Independents cut loose. Blood rushed back into the political center. Republicans found themselves marginalized by their own polarizing strategy. The wiser among them now understand that the only way back is through the middle.

McCain stands unrivaled among Republicans as a proven magnet for moderate and independent votes. He has a long record of working and talking across party lines. He not only understands independents, he needs them, because polarized partisans don't trust him (for good reason). Even if he wanted to, he couldn't run a Bush-style "50 percent plus one" strategy of playing to the base and picking off just enough moderates. "He may be able to bring the party back to the center, and that would be deeply useful," says Steve Bell, who, as a longtime senior aide to Sen. Pete Domenici, R-N.M., has observed McCain for years. (Domenici has endorsed McCain, despite past encounters with McCain's epithet-laced temper.)

Democrats control both chambers of Congress and are expected to consolidate their majorities this year. In 2009, a Republican president is unlikely to be able to scare Democrats into submission, as Bush did for a while. Instead a GOP president would have to do a delicate job of triangulating between the Democratic majority and a sometimes truculent Republican base.

With his long record of working across party lines—on campaign finance law and global warming and judicial appointments and much more—McCain is uniquely equipped to provide Republicans with the last thing they expected to see post-Bush: a productive Republican presidency. "I think we might actually get some stuff done," Bell says.

Most Republicans understand that their loss of credibility on spending restraint and fiscal responsibility has damaged the Republican brand. Wise Republicans understand, further, that supply-side dogmatism has become part of the problem. The supply-side movement made sense when the top tax rate was 70 percent, taxes rose with inflation, and tax cuts were only one part of a program that also included deregulation and lower spending. It stopped making sense when Bush-era Republicanism turned it into an obsession, fixated on the idea that if you just cut taxes and then cut them some more, lower spending, smaller government, and shrinking deficits will follow.

McCain has a long record of vocal opposition to pork-barrel spending and congressional earmarks; he makes a point of calling for entitlement reform; and he is not a supply-sider, having voted against both of Bush's biggest tax cuts. Supply-siders hate that, and it's true that he has now rallied to them with expensive and unpaid-for promises to extend the Bush tax cuts and abolish the alternative minimum tax. Still, McCain's heart belongs not to the supply-side absolutism of the Bush era but to the tightfisted rectitude of the Eisenhower era. If anyone has a shot at restoring Republican fiscal credibility, it is McCain.

Wise Republicans understand that Bush has severely damaged both the sustainability and the reputation of the war on jihadism by trying to run it on presidential fiat, by claiming effectively unlimited power to detain anyone forever, and by cratering the world's faith in American values. In the eyes of too much of the world and too many Americans, Abu Ghraib, waterboarding, and contempt for Congress have become hallmarks of the war on jihadism.

McCain is tailor-made to repair this damage. A torture victim himself, he stood up to his own president and party to pass the 2005 Detainee Treatment Act. He led this fight knowing that it would devalue his stock with Republicans. He likewise stuck out his neck to pass legislation that put military detentions and trials on firmer legal footing, again with no prospect of political reward.

Bush has regarded Congress and the courts as nuisances to be circumvented whenever possible. Perversely, if predictably, his insistence on strengthening the presidency at any cost has weakened it instead, and has left the war on jihadism balanced precariously on one legal leg. McCain has led the way back toward the constitutional and moral high ground, understanding that the war won't be sustainable unless it is firmly rooted in America's best legal and humanitarian traditions.

Wise Republicans recognize that immigration-bashing—yes, even when ostensibly focused on illegal immigration -- produces an addictive political rush, followed by long-term debilitation. If the party effectively writes off Hispanics and sets itself up as the enemy of an open, compassionate America, it is doomed. McCain, despite his recent "enforcement first" conversion, remains one of the party's two major spokesmen for a pro-immigration future. The other is Bush, but he is a spent force. If anyone can negotiate a path through the immigration thicket and build a consensus that Republicans and the country can live with, it is McCain.

So McCain offers Republicans hope of a revitalized center, a connection to independents, a productive presidency, improved fiscal credibility, improved moral credibility, a restored constitutional balance, a firm instead of flimsy war on jihadism, and a way forward on immigration. You have to look back to Reagan to find such a serendipitous match between the man and the moment.

The eclectic McCain is a handyman, not an architect. His skills and positions are well suited to fixing the Bush-era mistakes and getting the country to listen to Republicans again. But he is not a man of ideas like Reagan, Barry Goldwater, or Newt Gingrich. He could lead the party out of the cul-de-sac and back onto the main road, but, at age 71, he does not look like the man to point it toward a new destination.

Still, in 2008 a lot of Republicans don't yet understand that they're lost. The first job of work is to loosen the grip of the party's ideological satraps and veto groups. Never mind whether he wins the presidency; just by closing in on the nomination, and by drawing boos at CPAC, McCain has begun cutting his party free.

© Copyright 2008 National Journal

Jonathan Rauch is a senior writer and columnist for National Journal and a frequent contributor to Reason. The article was originally published by National Journal.