The GOP race has devolved frequently into a shameless contest to see who can bash illegal immigrants the loudest. McCain, who represents a border state, has resisted this pandering to the Republican base. He supports giving illegals a pathway to citizenship, when taking a harsher position would clearly win him more primary voters.
The former prisoner of war in Vietnam has stood tall against the Bush administration's condoning of torture for enemy combatants. He dared speak out against former Defense Secretary Donald Rumsfeld's mismanagement of the war in Iraq - although McCain's willingness to keep U.S. troops there indefinitely is wrong, too.
McCain has shown an ability to learn from mistakes. Accused of intervening on behalf of a campaign contributor in the 1980s' savings and loan scandal, he later took up the banner of campaign finance reform. He waged a lonely battle in his party, pushing through the landmark McCain-Feingold law in 2002.
McCain was among the first in his party to treat global warming as a serious problem. He's also been a consistent fiscal hawk in Congress.
None of this is to say McCain is without flaws. He's been a little too cozy with Christian conservative leaders, who trashed his candidacy in 2000. And although McCain correctly voted against the Bush tax cuts of 2001 and 2003, he now embraces the idea of making them permanent, which would deepen deficits.
Such shifts show McCain is trying to curry favor with party conservatives, who torpedoed his presidential bid eight years ago.
There was a time in this race when it looked as if former New York Mayor Rudy Giuliani would carry New Jersey and Pennsylvania easily. No longer. Giuliani has run a strange campaign, bypassing early states and placing all of his chips on Florida's primary on Tuesday.
Giuliani's role in New York on 9/11 was admirable, but he hasn't made a compelling case for becoming commander in chief. While he did clean up the city, he also let racial divisions, especially with regard to cases of police brutality, widen. He also gained a reputation for vindictiveness, targeting political enemies big and small. Those tendencies would be disastrous on the national stage.
Former Massachusetts Gov. Mitt Romney just might be the candidate best equipped to deal with a looming recession. He has a strong record of sound fiscal management in government and in private industry.
But Romney has tried to be so many things to so many different constituencies, he's left voters with little idea of his core beliefs. Is he pro-choice, as he professed while governor, or pro-life, as he now claims? Is he the candidate who supported gun control in 1994, or the one who now bills himself as a committed friend of the NRA? It's not clear whether even Romney knows the answers.
Former Arkansas Gov. Mike Huckabee, a Baptist minister, is a worse choice. He engaged in borderline mockery of Romney's Mormon faith during the Iowa caucuses, and employed religious symbolism to win votes. The sooner he quits, the better.
For all these reasons and more, John McCain is clearly the strongest Republican for president.