The telephone survey, sponsored by MPR and the Humphrey Institute of Public Affairs, interviewed 763 likely voters last week and early this week.
Forty-eight percent said they support Democrat Barack Obama for president, compared to 38 percent for Republican John McCain. Three percent favored independent Ralph Nader and 1 percent supported Libertarian Bob Barr.
The margin of sampling error was plus or minus 3.6 percentage points.
Larry Jacobs, director of the Humphrey Institute's Center for the Study of Politics and Governance, said despite the double-digit margin, the race in Minnesota remains fluid. Jacobs said 10 percent of those polled were undecided, and supporters of each candidate said they might change their minds.
"This is not a poll saying Obama has a lock on Minnesota. Far from it."
"So this race is very much up in the air and up for play," he said. "This is not a poll saying Obama has a lock on Minnesota, far from it."
A Republican presidential candidate hasn't won in Minnesota since 1972. But Jacobs said the poll found McCain might be able to reverse that trend, if he selects Minnesota Gov. Tim Pawlenty as his vice presidential running mate. One in four of the undecided voters and initial-Obama supporters said they'd back a McCain-Pawlenty ticket.
"We were quite impressed by the impact that Gov. Pawlenty has on McCain's chances," he said. "Our analysis suggests that the McCain ticket jumps by 13 points by adding Gov. Pawlenty to the ticket. That is quite an impact."
The results show deep disapproval of President Bush's job performance and a view that the country is heading in the wrong direction. Both of those factors are helping Obama and hurting McCain. Age appears to be a negative for McCain, and lack of experience is hurting Obama.
The poll also found that 9 percent incorrectly believe Obama is Muslim and 42 percent did not know that Obama is a practicing Christian.
The economy tops the list of challenges facing the country.
Beverly Hoisington of Rochester said she knows McCain has more experience, but she's leaning toward Obama.
"I would hope that some of his ideas would be fresh," she said. "Add because I'm a senior, I hope some of my needs and concerns are his needs and concerns."
Another poll respondent, John Aho of Coon Rapids, identifies himself as an independent voter. Aho said he's undecided, but he's leaning strongly toward McCain.
"He is a common sense type person," he said. "He doesn't get carried away with things. He's calm. And his values are pretty much what I would call my own at the present time."
The MPR/Humphrey Institute results contrast sharply with three other recent polls that showed a much tighter contest in Minnesota.
A statewide survey last week by Rasmussen Reports found Obama leading McCain by 4 percentage points. SurveyUSA gave a 2 point lead for Obama. And last month's Quinnipiac University poll also showed Obama leading McCain by 2 points.
Polls are a snapshot of a moment in time, and Larry Jacobs said two of the other recent polls were conducted at a time when Obama was on vacation.
"Obviously Barack Obama was not on stage, and McCain had it all to himself," he said. "So you want to ask was that poll reflective of the general state of play in Minnesota? Because for the most part, polling over the three months before Barack Obama went on vacation showed the race as a double-digit Obama lead."
The poll found a sizable gender gap in Minnesota. Women voters preferred Obama over McCain by 16 points, while men were split nearly even between the two candidates.
Jacobs said race is a potential drag on Obama, but the impact is difficult to pin down. He said when voters were asked directly few said race would diminish their support for Obama. But when the question was put a different way, and people were asked whether race would be a factor for people they know, 13 percent said it would.
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