PRINCETON, NJ -- Democratic front-runner Barack Obama has a four-point advantage over presumptive Republican nominee John McCain among registered voters residing in states that were competitive in the 2004 election. Obama has a comfortable lead in states John Kerry won comfortably in 2004, as does McCain in states George W. Bush won easily.
The analysis is based on aggregated data from 优蜜传媒Poll Daily tracking in April, consisting of interviews with more than 13,000 registered voters. 优蜜传媒considers states where Kerry won the 2004 presidential vote by six percentage points or more to be safe Democratic or "blue" states, and states where Bush won by six percentage points or more to be safe Republican or "red" states. The remaining states -- in which the winning candidate prevailed by five percentage points or less -- are considered competitive or "purple" states.
Based on this definition, the purple states include New Hampshire, Pennsylvania, Ohio, Michigan, Wisconsin, Minnesota, Iowa, Florida, Colorado, Nevada, New Mexico, and Oregon.
Hillary Clinton also leads McCain by the same 47% to 43% margin among purple-state voters. But she does not fare quite as well as Obama does in blue states, and she trails McCain by a slightly larger margin than Obama does in red states.
McCain and his supporters can take solace in that there are more red states, more voters, and thus, more electoral votes in those states. So even though he trails by four points in the most competitive states, he is down by only two points to Obama (46% to 44%), and is down by just one point to Clinton (46% to 45%), among registered voters when all states are combined.
According to 2004 election statistics, 36% of all voters in that election resided in red states, 33% lived in blue states, and 31% in purple states. So the Democratic candidate is starting out at a disadvantage, everything else being equal. Thus, in order to win the election, the Democratic candidate probably has to defeat the Republican by at least a couple of percentage points in the competitive states, assuming the vote distributions in the red and blue states stay relatively constant. The Republican can probably win by essentially breaking even in the competitive states, as Bush did in 2004. (While this analysis focuses on the popular vote, the electoral vote results should generally follow a similar pattern, in which the candidate who wins a greater share of the popular vote in the competitive states will probably also win a greater share of the electoral votes in those states.)
The final 2004 popular vote results were more polarized than the current poll data suggest is the case now. McCain is not faring as well as Bush did in 2004 in red states, where Bush defeated Kerry 59% to 40%. And Obama only matches the 13-point advantage Kerry had in blue states (56% to 43%). The two candidates essentially split the vote in the most competitive states in 2004, with Bush winning 50% and Kerry 49%.
One reason for the difference is that the 2004 data are based on actual voters, while the current data are based on registered voters. Registered voters may not be as firmly attached to their party affiliations as are actual voters. It's also possible that the vote will correlate more highly with party support once the general-election phase of the presidential campaign gets fully under way.
Implications
It's likely that the 2008 election will be fought in the battleground states, just as in prior elections. Gallup's election polling to date suggests that the presidential election could be very close, because neither McCain nor his Democratic rivals have maintained much of a lead in recent weeks.
The analysis of competitive states adds insight into how the candidates are doing beyond the overall vote figures. A candidate must do reasonably well in those states to have a chance at winning. For example, McCain could open up a significant lead in the national vote based on a very strong performance in the red states, but that would not mean he was better positioned to win than if he were not doing as well in the red states but doing better in the more competitive states.
As of now, Obama and Clinton have an advantage over McCain among voters in the competitive states. Given that more states fall into the Republican column than into the Democratic column, the Democratic nominee probably needs to maintain that advantage in order to prevail in enough purple states to gain the electoral vote advantage in November.
Survey Methods
Results are based on aggregated telephone interviews with 13,217 registered voters, aged 18 and older, conducted April 1-15, 2008, as part of 优蜜传媒Poll Daily tracking. For results based on the total sample of registered voters, one can say with 95% confidence that the maximum margin of sampling error is 卤1 percentage point.
For results based on the sample of 4,894 registered voters residing in states that George W. Bush won the 2004 presidential voting by 6 or more percentage points, the maximum margin of sampling error is 卤2 percentage points.
For results based on the sample of 4,375 registered voters residing in states that John Kerry won the 2004 presidential voting by 6 or more percentage points, the maximum margin of sampling error is 卤2 percentage points.
For results based on the sample of 3,948 registered voters residing in states where the margin of victory for the winning candidate in the 2004 presidential voting was 5 percentage points or less, the maximum margin of sampling error is 卤2 percentage points.
Interviews are conducted with respondents on land-line telephones (for respondents with a land-line telephone) and cellular phones (for respondents who are cell-phone only).
In addition to sampling error, question wording and practical difficulties in conducting surveys can introduce error or bias into the findings of public opinion polls.
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