During the CNN debate for Republican presidential candidates this week, James Fallows noted in passing that he hopes “no one outside the U.S. is allowed to watch this hilarious but depressing spectacle.”

I’m fairly certain Fallows wasn’t talking about the network’s theatrics.

It’s awfully difficult to keep a close eye on the GOP field and not marvel at its ineptitude. When was the last time a major political party produced a slate of presidential candidates this embarrassing?

Put it this way: Mitt Romney was a one-term governor so disliked by his constituents he was afraid to run for re-election; the head of a vulture-capitalist firm known for breaking up struggling companies and firing their employees; an uncontrollable flip-flopper who’s taken both sides of every issue; and is widely disliked within his own party, despite having been a non-stop presidential candidate for nearly six years.

And yet, Steve Kornacki this week accurately described Romney as “one of the weakest front-runners either party has ever seen” who’s still very likely to win the GOP nomination.

If President Obama had an 80% approval rating and was a near-lock for a second term, this would make a lot more sense. Real candidates would take a pass and focus their efforts on 2016, when a wide-open cycle could offer better odds. But that’s clearly not the case — President Obama is vulnerable and the Republican nomination is worth winning.

But who’s running? The now-set field is made up of Romney, another befuddled Texas governor, a guy who ran a mafia-themed pizza company, a radical libertarian House member, a wild-eyed conspiracy-theory House member, a disgraced former House Speaker, a defeated former senator who doesn’t even want you to Google his name, a libertarian former governor who can’t get invited to debates, and a former Obama administration official who’s credible but has been deemed beyond consideration by the party faithful. Most of these nine are hard pressed to explain why they’re still even bothering to run.

How in the world did this happen? Jonathan Bernstein had a good piece on this the other day, asking a similar question: “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.

These are both persuasive points. On the first, while fields traditionally winnowed after early nominating contests, we now see GOP contenders running and quitting well ahead of Iowa. Tim Pawlenty, for example, was a credible contender, but he lacked staying power. The same forces kept other credible candidates, including Mitch Daniels and Haley Barbour, from even launching campaigns in the first place.

As for the overabundance of fringe vanity candidates, many of these conservative personalities know national campaigns, even pointless ones, means exposure and post-campaign business opportunities. Bernstein explained, “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.”

I’d add just one other factor: the failure of the Republican Party in the Bush era was costly to the party in several ways, including the thinning of the GOP bench. Virginia’s George Allen, after all, was supposed to be a major national player, right up until he was caught up in a Democratic wave — one that covered two cycles and ended many Republican careers.

The result is an ignominious field for the books. This is not to say one of these candidates can’t win the White House next year; one very well might. But it’s hard not to take a good look at these folks and shake one’s head in amazement.

Steve Benen

Follow Steve on Twitter @stevebenen. Steve Benen is a producer at MSNBC's The Rachel Maddow Show. He was the principal contributor to the Washington Monthly's Political Animal blog from August 2008 until January 2012.