Has Barack Obama's support slipped in the month of July?

There has been speculation -- reasonable and based on some empirics -- that Barack Obama may have slipped some in the match-up against John McCain in the presidential preference measurement. This slippage appears to have occurred since about July 4th weekend. For example, the fivethirtyeight.com model shows some downturn, and Michael Barone also appears to think so. The tracking polls by Rasmussen and Gall Up show the race to be with in 1-2 points.

However, I am not certain that the preference measurement data are clear on this matter. I think that we need to get some new preference data from Ohio and Indiana, and that will present a more clear pictures, The last preference measures from Ohio and Indiana showed Obama to be in slight lead (2-4 points) in Ohio, and essentially tied in Indiana. Here is my thinking --

(1) It is true that Obama's lead has shrunk in Maine from 20 plus points to about 9 points, it is also true that McCain's lead has ballooned to 20 plus points from about 9 points in Kansas (Rasmussen reports.) But it is also true that Obama's lead in California has expanded to 20 plus points from single digits (Field poll) and to double-digits in most East-coast states and robust numbers in Michigan (Quinnipiac, Sienna, Strategic Vision polls and Survey USA polls.)

(2) Michael Barone argues (July 16th) that "...if one assumes McCain is running a little stronger now, in which states would he be overtaking Obama, assuming a uniform rise across the country? In the South, Virginia (13 electoral votes). In the West, Colorado, Montana, New Mexico, and Oregon (24 electoral votes). In the Midwest, Indiana and Ohio (31 electoral votes). "

But recent preference measures (polls) taken after July 4th weekend show that Obama is leading by 4 points (about the same lead as in June) in Colorado, by about 9 points in Oregon (may be even a little bigger lead than in June), and he is tied with McCain in Virginia (about the same status as in June). There have not been preference measures in Montana, New Mexico and Indian and Ohio in the month of July. (Source, see RealClear Politics data). In any case, Barone's inference is inconsistent with data -- McCain is not leading in any of the states mentioned by him.

The state-by-state polls still appear to show the presidential race to be where it was in the month of June. Ohio will be a big one -- new polling data from Ohio will provide greater clarity.