03/26/2007 03:55 pm ET Updated Dec 06, 2017

Fred Thompson in '08?

(UPDATED 3/27/07: The new USAToday/Gallup poll is now out and it finds support for Thompson at 12%. I've updated the graph above accordingly. I've not changed the text below. The Gallup result just strengthens that argument.)

The unsettled nature of the Republican presidential nomination race can be seen by the impact of talk that former Tennessee Senator Fred Thompson is considering entering the contest. There has been little polling on Thompson-- only three questions in two years-- but the latest Zogby telephone poll (3/22-26/07)l finds Thompson at 9% support, tied with former Massachusetts Governor Mitt Romney. That a non-candidate can leap to a tie for fourth place based on only a suggestion that he might run, says more about the state of Republican preferences than does former New York City Mayor Rudy Giuliani's continuing lead in the polls. While voters are willing to pick from a list of candidates, that so many will jump to Thompson shows preferences are far from settled.

Is 9% support a lot? Not in absolute terms, but compare that to the 9% Romney receives when fully committed to his campaign and after being an active candidate for many months. (I'm talking about how he has behaved, not the date of his various declarations.)

Or compare Thompson at 9% with Arizona Senator John McCain who held the support of just 13% of the Republicans in this Zogby poll. McCain held 17% in a January Zogby poll and 20% in Zogby's February poll. His support has been declining somewhat since January.

Former House Speaker Newt Gingrich was not included in the poll. Based on other polling, Gingrich has been holding a small two percentage point lead over Romney, so Thompson would appear to slightly trail Gingrich as well. In Zogby's January poll Gingrich was at 8% and at 7% in February. It is both unfortunate and puzzling that Gingrich was dropped from the latest poll, opening a window of doubt as to where his supports went when not offered the chance to support him in the survey question. Gingrich's supporters might have been more likely to jump to Thompson with Gingrich not on the list, inflating Thompson's support.

While the change in the candidate list makes a direct assessment of Thompson's support problematic, the instability of opinion among Republicans is clear in any case. While Giuliani's support has been rising recently, and he has led McCain in the vast majority of polls since 2004, there is substantial evidence that the party is open to an alternative "challenger" to emerge from the pack.

I should also note that Zogby finds 28% of Republicans unsure of their preference for the nomination, substantially more than most polls. The amount of undecided varies quite a bit across polls, making comparison of the absolute levels of support more uncertain than usual. For example, in the candidate trend plots below, Giuliani's support is estimated at around 36% and McCain's at about 22%, compared to Zogby's estimates of 27% and 13% respectively. If pushed, the undecided might be expected to pick familiar names, possibly boosting these two.

Thompson might, or might not, prove to be a formidable candidate if he officially got into the race, rather than simply encouraging speculation. But the amount of support he has picked up on such slim efforts shows that there is a great deal of room for change in the Republican contest.

The top four Republican candidates seem to generally continue recent trends-- Giuliani rising, McCain slipping and Gingrich and Romney continuing slow but steady rises. If we add Thompson to the plot below, he would overlap that latest Romney reading, with both at 9%.

It undoubtedly bears saying clearly that this is the first poll with Thompson included since his suggestion that he might run. We should never put too much confidence in a single poll, as the spread of points around the trend lines above demonstrates. The next poll may show less support or more support. Let's hope we get some new data soon so we can better assess Thompson's potential.

To see all the polling on all the presidential contenders, updated with the new Zogby data, click here. That page is updated with each new poll, and provides a handy reference point for all the latest national primary polling.

Cross-posted at Political Arithmetik.