A theory.

Newt Gingrich’s entrance into and Mike Huckabee’s departure from the 2012 race have both accentuated the flaws in the Republican presidential field, with numerous commentators viewing the current slate of candidates, in the words of one prominent GOP strategist, as the weakest since the one that produced Wendell Willkie. The Republicans’ mediocre field has been attributed to a host of factors, including timidity from stronger candidates wary of taking on President Obama as well as the GOP’s rightward movement, which has scared off or excommunicated electable centrists. Both are valid factors, but that the Republicans would have such difficulty in 2012 was predictable several years ago, well before Obama’s election or the rise of the Tea Party movement. It was the decimation of the national Republican leadership roster, thanks to Senate and gubernatorial losses in 2004 and 2006, that has deprived the party of viable contenders.

When it comes to presidential politics, the reality is that fields are generally set years before an actual election, as good nominees must have calibrated experience combined, critically, with impeccable timing. Politics geeks know about the 14-year presidential “freshness test,” which postulates that a candidate who has been around for too long is unlikely to ascend to higher office, as voluminous records create excessive baggage and older candidates who are professionally long in tooth but have trouble with voter appeal. (Consider the last four losing presidential candidates.)

Yet the freshness test stands somewhat incomplete, particularly in our media-saturated political climate, which can accelerate a politician’s career decline. Indeed, to win a presidential election, in addition to having an appealing, electable personality, a candidate should meet three key criteria: be of the right age (the sunnier side of 60, or close to it), come directly from the right office (Senate, governorship, or vice presidency), and have been elected last within a certain window (reasonably, within four to six years of the presidential race). There have been exceptions to these rules, like Ronald Reagan and Lyndon Johnson, but they are increasingly rare today. And these criteria can explain why the Republicans are struggling to find a real 2012 contender.

Excluding Gingrich and Ron Paul (who both arrived in Washington in 1979), the entire Republican field is actually relatively young (or, in Mitt Romney’s case, looks young), so the first criterion isn’t the issue. The problem for Republicans, rather, is that most of the people already in the fold or seriously being discussed as potential candidates—Gingrich, Romney, Tim Pawlenty, Rick Santorum—aren’t sitting elected officials. They’re retreads several years out of office and past their prime window; meanwhile, few others with the right credentials are waiting in the wings. (Michele Bachmann, for instance, doesn’t ring serious and also sits not in the Senate but in the House.)

Why are there so few potential Republicans candidates currently in office? The reason can be traced back to the 2004 and 2006 election cycles, which upended the GOP’s national bench. In 2006, when 36 governorships were up for grabs, Republicans elected just four new executives: Charlie Crist in Florida, Jim Gibbons in Nevada, Sarah Palin in Alaska, and Butch Otter in Idaho. Only the ultra-conservative Otter won reelection. (While Gibbons was toppled for broad incompetence and Palin quit in the middle of her term to become a celebrity, Crist probably had good national potential, but he was ousted for perceived centrist apostasy.) The Senate side was even worse for the GOP, as just one new senator was elevated: Bob Corker of Tennessee, a relative moderate (in today’s Republican caucus, at least) who pointedly refused a national run this year.

The 2004 elections were admittedly stronger for Republicans, as they elected seven new senators, of which six still serve. But this group is made up mostly of southerners and searing right wingers with limited national appeal, including Tom Coburn, Jim DeMint, and David Vitter. More important were the governor’s races, but, out of eleven offices up for grabs, Republicans elected only three new executives, just one of whom is still in office: Mitch Daniels, a figure many conservatives are now understandably pushing to run. (Potential nominee Jon Huntsman also won in 2004 and was reelected, but he quit to take a position in the Obama administration. As a result, the talented Huntsman has almost no chance of winning the Republican primary.)

Collectively, then, with the exception of Daniels, who is wavering about entering the race, Republicans have a virtually nonexistent crop of politicians whose time of service is within the right parameters to make a viable run for president next year. And, even if we widen those parameters and looked at how the GOP fared in 2008, things don’t get better. Republicans tapped no new governors that year and only two senators, Jim Risch and Mike Johanns, neither of whom, for reasons of geography and lack of charisma, will likely ever run nationally anyway.

But, as bad as it may look for Republicans, they can take heart in the future. In the 2010 midterms, the GOP elected 13 new senators and 17 new governors, of whom ten and twelve, respectively, are under 60—an impressive split that doesn’t even include conservative stars Chris Christie of New Jersey and Bob McDonnell of Virginia, who were elected in 2009. By contrast, Democrats elected just three new senators and eight new governors last year, of which only five are under 60. 2012 is expected to be just as bad for the Democrats’ farm growth; the party will be hard-pressed to elect many new senators, and, while eight of the 11 open governor’s offices are currently Democratic, just five—Delaware, Missouri, New Hampshire, Vermont, and West Virginia—are favored to return Democrats. And it’s also not clear whether even these politicians will have the interest or national appeal to stage a national campaign. Indeed, if Republicans can’t beat Obama, 2016 will be their better bet for taking back the White House.

Mark Greenbaum is a writer and attorney in Washington, D.C.

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