CNN Poll: Key Arkansas Senate race a dead heat

The poll shows that each candidate is winning his party's traditional political voting blocs, except Cotton appears strong with a key subset of the national Democratic Party's most faithful supporters -- a data point that is likely to raise a red flag among party elders and strategists.

While Pryor holds an 8-point advantage over Cotton with likely women voters overall, Cotton is favored by likely voters among white women by 11 points. Losing a key constituency to an opponent by such a large margin could be devastating.

"The bad news is that he seems to have opened up a new way to lose to Republicans by losing badly with white women," said a Democratic operative who knows Pryor but is not working on his race. "The good news is that is a segment of the electorate that tends to break Democratic, and he has time to close that gap. If he does, he wins."

For Cotton, one of his biggest weaknesses is with people who make under $50,000 -- not unexpected when you look at traditional political voting bloc alliances. Pryor has a 9-point lead over Cotton with this group.

The recent decision to include a measure on the November ballot that would increase the minimum wage in Arkansas from $6.25 to $8.50 by 2017 may help the incumbent by turning out more Democratic base voters, who often sit out midterm elections.

"The hope in Democratic circles is that those lower-income voters will turn out to vote themselves a raise, and while they are in the voting booth, they will wind up casting a ballot for Pryor as well," CNN Polling Director Keating Holland said.

When it was announced that the measure would be on the ballot, Pryor issued a statement calling it a "common sense proposal to put more money in the pockets of hardworking families across Arkansas."

Much like other critical Senate Democratic re-election bids, President Barack Obama is seen as a drag, not a plus, for Pryor in November. Obama's approval rating in Arkansas is just 33%, while 60% of registered voters disapprove of how he is handling his job. While Pryor voted for health care reform, he has opposed the President on other issues in the Senate and has not embraced him on the campaign trail.

For some Republicans, though, it is puzzling that Cotton doesn't have a bigger lead over Pryor.

While Pryor is among the centrists in his party and is the son of a former governor, if you look at the most recent voting trends, they would seem to clearly favor the Republican.

Cases in point: Mitt Romney beat Obama by 24 points in 2012, and four years earlier, John McCain carried the state by 20 points. In 2010, Pryor's then-Democratic colleague, Sen. Blanche Lincoln, lost her seat to GOP Rep. John Boozman by 21 points.

Beyond the favorable GOP voting trends, Cotton has a resume that jumps off the page. He deployed to Iraq and Afghanistan, is Harvard educated and hails from a longtime Arkansas family. Yet, there is a thought among some Republicans that Cotton has failed to connect personally with voters.

"It is often said that people vote with their wallet, but it also is true that people decide based off of whom they would rather sit down and have a beer with," said a veteran GOP congressional and campaign operative. "Likability matters. Mark Pryor is a likable guy. Tom Cotton's got to turn on the charm in the closing weeks."

In the so-called middle, Cotton is winning independent voters by 20 points, but it is unclear how nonpartisan these voters may be. A closer look at the data suggests that these voters appear to be more conservative-leaning than liberal-leaning.

"In some states, tea party supporters in recent years have tended to describe themselves as independents rather than Republicans since they don't feel comfortable with the GOP as it is currently structured," Holland said. "It's unclear if this is true in Arkansas, but one piece of evidence to support it is that more than half of self-described independents say they are conservative and only eight percent call themselves liberal."

In the end, the winner of this race will be the person who turns out more of its supporters, while at the same time convincing crossover voters to support their campaign. The poll shows that Pryor has an edge in this category as 9% of Republicans said they are backing or leaning towards voting for him, while 5% of Democrats said they are backing or leaning toward Cotton.

As for the overall electorate, 71% of likely voters said they have made up their minds, leaving about 24% who are open to changing their minds.

The poll was conducted for CNN by ORC International, which interviewed 1,010 adults in Arkansas, including 523 likely voters, by telephone between August 28 and September 2. The sampling error for results for likely voters is +/-4.5 percentage points.

Friday's poll was the second CNN/ORC International Poll of a Senate battleground state this week that shows the Republican candidate with a slight edge.

Senate Minority Leader Mitch McConnell holds a 4-point advantage over his Democratic challenger Alison Lundergan Grimes. The GOP needs a net gain of six seats to take control of the Senate.