Mitt Romney’s running mate is going to rank very low on the list of what’s on voters’ minds in November. Political journalists are obsessing about whom he’ll pick anyway, because it is one of the biggest remaining unknowns about the race. Even better, it creates opportunities for speculation.

The speculators place high value on excitement. They’re talking up potential vice-presidential candidates who would represent a demographic first, or an ideological statement, or play to a state or region. My guess is that Romney is looking at this in a completely different way.

If I’m right, Romney will be looking for three qualities that don’t generate buzz. He’ll want someone he considers able to step into the role of president if needed; someone loyal; and someone with whom he feels personally comfortable. Romney’s main political consideration will be whether the running mate reinforces the message that he is a dependable, competent, reassuring candidate who will oversee an administration with those same features.

He will of course want someone who is acceptable to conservatives, evangelicals and other Republican groups. He will not, however, be desperate for a running mate who appeals specifically to them, because he thinks that they’re likely to vote for him over President Barack Obama anyway.

Taken together, these criteria work against conservative heartthrob Marco Rubio, the senator from Florida. Romney and Rubio don’t seem to have much of a personal relationship. Rubio has no executive experience. And Romney probably considers Rubio unseasoned, which he is. Rep. Paul Ryan, another conservative favorite, has more experience but has never been an executive or even won a statewide race. Those weaknesses may take him off the list.

The criteria just mentioned work in favor of an all-white- guys ticket. Most Republican politicians, and especially the more-established ones, are white guys, after all. So unless Romney puts a thumb on the scale for diversity, he is likely to end up with one of them.

Of the names being mentioned for vice president, seven seem to meet these criteria: New Jersey Gov. Chris Christie, Louisiana Gov. Bobby Jindal, Arizona Sen. Jon Kyl, Virginia Gov. Bob McDonnell, former Minnesota governor Tim Pawlenty, Ohio Sen. Rob Portman and South Dakota Sen. John Thune.

Although Christie seems to want the slot, he may have taken himself out of contention by repeatedly saying he isn’t ready to be president. That’s a comment that would be hard to walk away from.

Most Republican insiders think highly of Portman, and many say that picking him would generate a little helpful press in his home state. Because he served in George W. Bush’s administration as budget director and trade representative, his selection would also make it easier for the Obama campaign to claim that Romney is just trying to go backward - a charge that Republicans have not yet figured out how to answer.

Like Portman, McDonnell comes from a swing state where he’s popular. Some Republicans worry, though, that Democrats and the national press would be able to portray him as a social-issues extremist because of some of the abortion bills Virginia legislators have pushed.

Kyl is a long shot. He is well-respected, and Romney may value his years of work on national-security issues. Conservatives around the country aren’t begging for him to be on the ticket - most of them don’t know who he is - but if he were picked they would discover that he has a very conservative record on economic and social issues.

Pawlenty and Thune have been touted as potential running mates for some of the same reasons. They’re both from the upper Midwest, evangelical Christians and considered attractive. None of those is an especially good reason for putting either of them on the ticket.

There are better reasons for picking Pawlenty. As a two- term governor he reined in spending and took on public-sector unions. Thune has fewer accomplishments, having no signature legislative issues. Pawlenty has a good relationship with Romney, for whom he has been tirelessly stumping. Having run for president, Pawlenty has a better sense than any of the other people on the list about what that level of politics is like. His working-class background is a modest plus, and he is a more energetic speaker than Portman.

Jindal is the only potential vice-presidential candidate who hits the sweet spot: He is simultaneously a conservative favorite, demographically interesting (he’s a Catholic of Indian ancestry), and a reform-minded, competent governor. Pawlenty and Jindal, then, are the two candidates with the strongest cases.

If Romney picks Kyl, McDonnell, Pawlenty, Portman or Thune - anyone on this list, that is, but Christie or Jindal - he should make the announcement soon. None of those guys is going to excite the Republican convention, so there is no point in waiting for it. The longer Romney waits, the more conservatives will speculate about candidates like Rubio and the more many of them will feel let down by a choice that isn’t designed to give them the rush of momentary excitement.

If Romney is going to do something boring, in other words, he should at least do it in a novel way.

Ramesh Ponnuru is a Bloomberg View columnist and a senior editor at National Review.