Take a moment to imagine the following GOP presidential field: two popular, former big-state governors (one a former U.S. Treasury secretary, the other a hero of the conservative movement), two Hall of Fame senators (one of them a former vice-presidential nominee, the other a future White House chief of staff), a former CIA director, ambassador, and party chair, and a couple of miscellaneous House members. Not bad, right? That’s your Republican candidate field in 1980: Ronald Reagan, John Connally, Howard Baker, Bob Dole, George H.W. Bush, John Anderson, and Phil Crane. It would produce five presidential nominations and three victories. Or look at what the GOP could choose from in 1996: In addition to the nominee, Dole, the field included five perfectly respectable senators or governors.

Republicans would be forgiven for feeling envious of primary seasons past. This year, they only have two legitimate candidates—Mitt Romney and Rick Perry—with conventional credentials and campaigns that place them within the mainstream of their party. Beyond that, there are a collection of vanity candidates, people who appear to be auditioning for a show on Fox News, and a few who are seriously out of step with their party’s ideology.

Why is this year’s Republican presidential field so, well, weird? While each election year field is subject to its own particular constraints and quirks of history, today’s wacky Republican field is also the undeniable product of two long-brewing trends within the party. First, GOP elites have become ruthlessly efficient at winnowing the field of serious contenders. At the same time, however, the growth of the market for conservative books, television shows, and speaking engagements has made a presidential run a good brand-builder for those not seriously seeking to be president but eager to exploit that market.

First, when it comes to the winnowing process, conventional wisdom has it that the role of Iowa and New Hampshire is to separate the wheat from the chaff. And on the Democratic side, that’s still how it works: In 2008, candidates with conventionally acceptable credentials including Joe Biden, Chris Dodd, Bill Richardson, and John Edwards all contested the Iowa caucuses but dropped out shortly after. On the Republican side, however, that’s changed. As far back as the 1996 race, two of the five losing candidates, California Governor Pete Wilson and Pennsylvania Senator Arlen Specter, never actually made it to Iowa. Dan Quayle, Lamar Alexander, and Liddy Dole all made the same decision to drop out pre-Iowa in 2000, while Tommy Thompson and Sam Brownback did it again in 2008.

This time around, the trend of serious GOP candidates dropping out (or not even running) is even more pronounced. Tim Pawlenty was a serious candidate who didn’t make it to Iowa, and Haley Barbour was all-but-announced before he changed his mind. Moreover, others (John Thune, Mitch Daniels, Sarah Palin, and Chris Christie) took a good look around, but chose not to become full-fledged candidates. It’s certainly possible that family considerations or something equally personal or random made the difference, but in at least some of these cases what likely happened was that key party actors—everyone from state party chairs to major donors to well-known and influential activists—perceived as necessary to win the nomination dissuaded these candidates and potential candidates from getting involved. We know this was the case when it comes to the failure of active candidates such as Pawlenty and Barbour to collect endorsements and raise money, and we can deduce it about the rest of the candidates from their reported efforts to consult with party leaders before making their decisions; presumably their choices might have been different had they heard more positive things. In other words, the Republican field of serious candidates is increasingly getting winnowed down well before actual voters ever get involved.

At the same time, however, there’s been a marked increase in fringe candidates who are “running for president” for reasons other than actually attempting to obtain the Republican nomination. There have always been ideological minorities who used the process to press their views or issues, with Ron Paul and Gary Johnson just the latest version of that. But what’s relatively new, and is now apparently more attractive, is using the presidential race as a way to create or build one’s brand in the conservative marketplace—what Jonathan Chait calls “business plan” candidates. Their incentive is to stake out the most extreme positions and court controversy in order to get themselves noticed by the most partisan customers of conservative books, talk shows, and other products, instead of developing carefully constructed issue positions designed to build party-wide support; their role model is Ann Coulter, not Ronald Reagan or Bob Dole.

We’ve seen these types before in both political parties (Alan Keyes, Al Sharpton, and perhaps Rudy Giuliani), but now the GOP field is lousy with them, from Newt Gingrich to Rick Santorum to Michele Bachmann to the man of the hour, Herman Cain. Of course, some of these “candidates” may think of themselves as serious contenders or, perhaps, ideological crusaders. But their behavior reveals them to be more concerned with selling books or getting a syndicated radio show.  

So is this new kind of presidential field—one or two serious contenders, a lot of goofballs—here to stay? My guess is that Republicans will be dealing with this situation for many elections to come. Winnowing early among serious candidates is generally thought to be good for the party; it’s not clear why party actors or insiders would want to end that trend. And I suspect that the combination of cable television—always thirsty for presidential campaign news, even if it has to settle for fourth-tier candidates—and online campaigning and fundraising has lowered the costs of entry and increased the rewards for “business plan” candidates. Moreover, the first trend encourages the second one; if Pawlenty, Thune, and Barbour were all running now, some of the fringe candidates wouldn’t poll high enough to get invited to debates and their cable news exposure would plummet.

The result of all this is some very odd debates, as well as a lot of confusion about what’s actually happening in the presidential race. It probably also looks bad for the party to have a big spotlight shining on a bunch of people competing to get Fox News contracts by providing the wildest accusations and the nuttiest rhetoric. But the good news for Republicans is that no one is likely to remember the crazy things that Newt or Bachmann said once general election campaigning begins in earnest, while the effects of winnowing mean that the nomination may be settled quickly once primary voting starts. And, at the very least, it keeps the primary debates interesting.

Jonathan Bernstein blogs at A Plain Blog About Politics.