...then how does the Republican presidential field shake up?
Poll after poll (for whatever good they are at this point in any presidential race) indicates that former Massachusetts governor Mitt Romney is the preferred choice of Republican voters.
But media story after media story reports that Mr. Romney's lead is fluid. The latest report was delivered today by the Los Angeles Times, which noted he has a "precarious" perch atop the GOP field.
Along the same lines, the Washington Post notes that every Republican candidate has faced little scrutiny, as he or she has built their campaigns. But that is about to change.
Without question, the news today that Texas governor Rick Perry intends this weekend to indicate he's running but not declaring his official candidacy adds some spice to the campaign. He almost certainly will become the darling of social conservative Republicans who are skeptical of Mr. Romney and almost every other current Republican seeking to dump Barack Obama.
At the risk of oversimplification, the GOP candidates (and I'm not listing all of them) belong in one of three camps.
The "let's talk business" camp is led by Mr. Romney. Another former governor -- Jon Huntsman -- would be the second choice at the moment.
The "tea party" camp is led by Michele Bachmann, but Ron Paul isn't far behind in terms of name recognition. At this point, however, he is well behind in the polls.
The "social conservative" camp lacks a real leader; and because it is influential in determining the party's nominee, it is looking for someone to rally around. Currently, Rick Santorum is the most prominent social conservative, but no one expects him to be a lasting player in the Republican race.
Upon reading those preceding paragraphs, you should not conclude that Mr. Romney, Ms. Bachmann and Mr. Perry will be the final three Republican candidates. But you should conclude that they will generate more media coverage, collect more money and project the "I am electable" persona.
In doing so, the latter two will sharpen their attacks on Mr. Romney. Yes, he might be on a "precarious" perch; but for now he is the only candidate who -- to shamelessly borrow a sports term -- is ranked No. 1.