There is almost exactly one year to go until the Iowa caucuses, which are tentatively scheduled to take place on Feb. 6, 2012. No mainstream Republican candidate has yet declared for the presidency, but that is sure to change soon, perhaps as soon as there is a lull in the news — something we have not had in weeks, because of the Tucson shootings and the Egyptian protests.

The Republican field may eventually grow to be fairly large, so it would be useful to examine the landscape through a technique I have used in the past: locating the positions of the potential candidates spatially.

One dimension is obvious: we can classify the candidates from left to right, from relatively more moderate to relatively more conservative. But another dimension that is often salient in the primaries, and perhaps especially so for Republicans next year, is what we might think of as the insider/outsider axis: whether the candidate is viewed as part of the Republican establishment, or as a critic of it.

Let me show you the chart, and then we can begin to work our way through it:

One can certainly debate exactly what it means to be a moderate or a conservative, and exactly where any particular candidate falls along this spectrum. Likewise, the insider/outsider dimension is somewhat blurry: is a potential candidate like Senator Jim DeMint of South Carolina, who aligns himself with the Tea Party but is also an influential senator, a part of the Republican establishment or an opponent of it? So my placement of the candidates is necessarily approximate.

With that said, it is exceptionally important to consider how the candidates are positioned relative to one another. Too often, I see analyses of candidates that operate through what I’d call a checkbox paradigm, tallying up individual candidates’ strengths and weaknesses but not thinking deeply about how they will compete with one another for votes. If you like, you can think of the circles on my chart as stars or planets that exert gravitational forces on one another, seeking to clear their own safe space in the galaxy while at the same time stealing matter (voters) from their opponents.

There are two more kinds of information embedded in the chart. First, the area of each candidate’s circle is proportional to their perceived likelihood of winning the nomination, according to the Intrade betting market. Mitt Romney’s circle is drawn many times the size of the one for the relatively obscure talk-radio host Herman Cain because Intrade rates Mr. Romney many times as likely to be nominated.

(I should note that there are several cases in which I am in considerable disagreement with the bettors at Intrade about the viability of each candidate. But using their figures as the basis for drawing the circles at least lends some objectivity to the assessment.)

I have excluded candidates like Gov. Chris Christie of New Jersey or Jeb Bush of Florida who have strongly denied any interest in running in 2012, even though some of them trade at nonzero values on Intrade.

Finally, the color of each circle reflects the region the candidate is from: blue for the Northeast, red for the South, green for the Midwest, and yellow for the West.

Does this matter, by the way? I suspect it is somewhat overrated as a factor in the race — the notion, for instance, that voters in Iowa will have any special affinity for a candidate from South Dakota seems tenuous to me — but for parts of the country that have a strong sense of regional cohesion, like the South and perhaps New England, it is worth considering.

Let’s proceed to consider the candidates by working through the four quadrants of our “galaxy.”

Conservative Insiders These are mainstream, conventional conservatives who will typically have jobs as governors or, especially, senators. Emblematic of the group is Senator John Thune of South Dakota. There is nothing especially distinct about Mr. Thune, whose chances I consider to be somewhat overrated. To some extent, though, that may be the point: he can excel at the areas that establishment candidates are typically good at, like fundraising and garnering endorsements, while at the same time being inoffensive to both moderate and conservative voters. An analogy can be drawn to John Kerry in 2004, an establishment liberal senator who won his party’s nomination under similar circumstances, while other candidates imploded.

The Washington establishment, of course, has not been popular of late — and Mr. Thune has cast some votes that he will have to answer for, like the ones on the federal bailouts. Still, the space surrounding Mr. Thune is not terribly crowded.

The other candidate who clearly seems to fit into his quadrant is Gov. Haley Barbour of Mississippi, but Mr. Barbour may have difficulty appealing to voters outside the South, especially after his recent comments about the civil rights era.

I have also placed Newt Gingrich in this quadrant, but there is a fair amount of distance between him and Mr. Thune, both stylistically and ideologically. Mr. Gingrich is a difficult case, a former Speaker of the House (it’s hard to get more establishment than that) who has more recently aligned himself with Tea Party groups.

Conservative Outsiders. Central to any discussion of this group is, of course, Sarah Palin, the former Alaska governor. But Ms. Palin, if she runs, may find herself in a crowd. There are several potential candidates in her orbit, like Mr. DeMint, Representative Michele Bachmann of Minnesota, Rick Santorum of Pennsylvania, and perhaps Mr. Gingrich; these candidates may compete with her for voters whether or not they are viable themselves.

Meanwhile, there is Mike Huckabee of Arkansas, an old-fashioned populist whom voters see as more moderate than Ms. Palin, especially on economic issues. The constituencies of Mr. Huckabee and Ms. Palin are not exactly the same — she cannot match his appeal to evangelical conservatives, while he may not match hers to the Tea Party. But polls nevertheless suggest that voters who have Ms. Palin as their first choice often have Mr. Huckabee as their second, and vice versa. If either were to stay on the sidelines, the other would become a much more formidable candidate.

Moderate Insiders. This quadrant may also become quite crowded. Two years ago, I placed Mitt Romney, a former governor of Massachusetts, slightly more to the conservative than the moderate side of the spectrum. But between his restraint in latching on to the Tea Party and some of the other causes of the conservative movement, and his having signed a health care bill while in the governor’s office that bears some resemblance to the one passed last year by the Democratic Congress, Mr. Romney seems likely to be branded as a moderate, whether he likes it or not. With that said, Mr. Romney is not so far removed from Mr. Thune, and the two candidates may compete with one another for support in the Republican establishment.

Perhaps of more immediate concern to Mr. Romney is a former Utah governor, John Hunstman, who may run for the presidency now that he is resigning from his post as ambassador to China, effective April 30.

Mr. Huntsman faces some significant hurdles — his name recognition is not terribly high outside Washington and his home state, and if he cannot begin to concentrate on his campaign until May, he may not be able to put together a strong campaign team or raise enough money. Also, his having served in Barack Obama’s administration could make his positioning awkward on a number of levels.

Still, he is similar to Mr. Romney in a number of ways, including policy positions and more superficial attributes like his Mormon faith and his good looks. One nightmarish scenario for Mr. Romney is that Mr. Huntsman takes enough votes away from him to keep him from winning an important early primary like New Hampshire, Nevada or Florida, even though Mr. Hunstman is not likely to win the nomination himself.

Another candidate in the general vicinity of Mr. Romney and Mr. Hunstman is Gov. Mitch Daniels of Indiana, who has more explicitly embraced his moderation. He has called for a “truce”, for instance, on social issues, and expressed a willingness to consider tax increases to rectify a budget deficit.

Mr. Daniels’s position is interesting. While he has a reputation for being a policy wonk, a quality that we would ordinarily associate with an “insider” candidate, his willingness to take controversial stands in some ways credentials him as a critic of the party establishment. Also, to the extent that geography matters, there aren’t very many Midwesterners to directly compete with him, apart (to some extent) from Tim Pawlenty.

Moderate Outsiders. Except for Mr. Daniels, whom I place right at the insider-outsider threshold, this space is quite vacant, with only two potential libertarian candidates, Rep. Ron Paul of Texas and former gov. Gary Johnson of New Mexico, as well Donald Trump, who is considering a presidential run but who — oddly for Mr. Trump — has not attracted much publicity for it. One thing to consider about Mr. Paul and Mr. Johnson is that the votes they attract may come from people who would otherwise cast no vote at all in the race, considering how few other candidates are positioned anywhere near them.

The sparseness of this quadrant may be no accident: centrists of both political parties tend to work within the establishment rather than outside it. One who might have been an exception, Mr. Christie of New Jersey, has repeatedly denied any interest in running.

Tim Pawlenty I had trouble placing him in any of the four quadrants. As Jay Cost of The Weekly Standard points out, — Mr. Pawlenty enjoys something of a reputation as a moderate even though his positions are fairly conservative: he has pledged to reinstate the military’s “don’t ask, don’t tell” policy, for instance. Likewise, Mr. Pawlenty seems to keep Washington at arm’s length while having supporters within the Republican establishment.

I have been skeptical about Mr. Pawlenty’s candidacy, in large part because his personality is not terribly dynamic and he has had some trouble creating a strong brand for himself; sales of his book “Courage to Stand”, for instance, have been quite weak. Still, he can be credited with a viable strategy: stay a safe distance off the lead lap, and hope for a multicar pileup ahead of him.

That Mr. Pawlenty has been among the first Republicans to build out his campaign infrastructure fits with that strategy — it would be valuable in the car-crash scenario, which implies a long, drawn-out nomination process. So does the fact that Mr. Pawlenty could plausibly position himself as conservative or moderate, insider or outsider, as the situation dictates.