If there is one thing we should have learned from the 2008 primary and general elections, to say nothing of 1996, it’s that being a good presidential candidate on paper is useless; you have to want it – want it badly enough to hire a serious staff, badly enough to trim a few positions and hard edges to fit the various demands of the primary and general electorates, badly enough to endure the most exhaustive efforts to tear apart your entire life for public entertainment, badly enough to spend endless weary hours fundraising and stumping in Iowa and New Hampshire and enduring crummy bus rides with grumpy reporters and town halls with cranks and half-wits and left-wing troublemakers. Your family needs to want it too – a man whose wife doesn’t want him to be president will not become president. It’s a big, life-consuming commitment, and you don’t do it halfway.

Add Haley Barbour now to the list of people who simply were not willing to make that 100% commitment, and Gov. Barbour knows himself and the task well enough not to pretend otherwise and run halfway:

“A candidate for president today is embracing a ten-year commitment to an all-consuming effort, to the virtual exclusion of all else,” Barbour added. “His (or her) supporters expect and deserve no less than absolute fire in the belly from their candidate. I cannot offer that with certainty, and total certainty is required.”

Gov. Barbour’s combination of folksy populism and gravitas, and his matchless rolodex as 1994 RNC chairman and 2010 RGA chairman – the two greatest years for GOP candidates across the country in a long time – would have made him a formidable entrant into the race. He had his weaknesses as a candidate too, which are moot now; the point is that a fully committed Barbour would have been a factor. Perhaps we should have suspected this was coming when his right-hand man at RGA, Nick Ayers, instead signed up for the Pawlenty campaign.

The roster of candidates who are genuinely serious GOP contenders – especially if you look at who has won a statewide election some time in the past decade – remains limited. All eyes will now turn to the people who remain on the fence (Sarah Palin, Mitch Daniels, Mike Huckabee) or denying they’re interested (Chris Christie, Rick Perry, Jeb Bush, Paul Ryan) to see who else might round out the field. In particular, the field now seems especially thin on Southerners for a party with so many officeholders in the region.

There’s still plenty of time to jump in; there’s perhaps less time now to hire staff and raise money. It’s early still; but as Yogi Berra said, it gets late early out there.