U.S. Sen. Al Franken leads his Republican challenger Mike McFadden by double digits, but that lead narrows dramatically outside the metro area and flips in northern Minnesota, according to a Star Tribune Minnesota Poll.

Franken gets the backing of 49 percent of likely voters, while McFadden gets 36 percent. Another 11 percent say they have not yet decided.

The first-term Democrat runs strongest in Hennepin and Ramsey counties, where two-thirds say they support him compared with 20 percent for McFadden. The outlying metro suburbs also tilt toward Franken.

But that lead vanishes in northern Minnesota, where 55 percent prefer McFadden to Franken, who gets a little over one third. The number of undecideds also dwindles to 5 percent. The state’s Iron Range region has become politically volatile in recent elections, with fissures deepening this year over controversial issues like the proposed PolyMet copper-nickel mining project that sometimes pit labor against environmentalists.

Despite GOP efforts to link Franken to the falling approval ratings of President Obama by painting him as a stalwart supporter of the president, Franken’s approval ratings at 53 percent eclipse those of Obama, who is at an all-time state low of 40 percent. Franken’s numbers have dropped two percentage points since February, but remain far above his nadir of 41 percent in September 2009 — two months after he took office following a lengthy recount in which he defeated former Sen. Norm Coleman by just 312 votes.

While McFadden remains on the offensive, criticizing Franken for voting for Obama’s signature legislation, the Affordable Care Act, and for voting with him 97 percent of the time, Franken has kept a low profile, deflecting criticism and continuing to distance himself from his satirist past with ads that portray himself as a serious, hardworking senator, compared with McFadden’s more lighthearted, slightly irreverent television spots. Voters like Tom Jones, 60, of Ogilvie, who describes himself as “primarily a Democrat,” will vote for Franken because of his head-down lawmaking and attention to issues like climate change and support for the Affordable Care Act.

GOP candidate Mike McFadden greeted supporters at a victory party in St. Paul. The poll found that more men favor McFadden.

“He’s looked after Minnesota, but I don’t think that’s the thing that’s most important,” Jones said. “What’s most important is that a senator deals with the entire nation. We’ll let the representatives deal with the home turf.”

50 days left

Carl Kuhl, McFadden’s campaign manager, said “Polls are a snapshot in time. The only poll we’re focused on is on Election Day.”

Franken campaign manager Matt Burgess called the results encouraging.

“These are promising, but we’re going to continue to work hard all the way until Election Day,” Burgess said. “We’ve always thought this was going to be a close race, and there are still 50 days left.”

Despite McFadden touting his business experience with Lazard Middle Market as a “problem-solver” and anti-establishment candidate poised to break Washington’s partisan gridlock, 70 percent of respondents said the challenger’s career as an investment banker makes no difference as to whether he’s more or less qualified to be a U.S. Senator.

Gary Gross, a conservative Republican from St. Cloud, says he’s indifferent to McFadden’s business background, but will back him for other reasons.

“At this point we need progrowth policies, economic policies, and Senator Franken hasn’t shown me that he’s interested in those types of things,” said Gross, 58, a self-employed blogger and researcher. “He’s pretty much gone along with the types of policies that have just kind of stuck us in the stagnation we’re in, and that would be my biggest reason for going with Mr. McFadden.”

The poll, conducted by Mason-Dixon Polling and Research Inc., interviewed 800 likely general election voters from Sept. 8-10 by land line and cellphones, with a margin of error of 3.5 percentage points.

Gaps between men, women

The more vigorous contest in the U.S. Senate race has produced high name recognition. Nearly every voter knows who Franken is, while 86 percent recognized McFadden. But nearly a third had neutral opinions of McFadden, compared to 15 percent who were neutral about Franken.

Retired investment banker Linda Barbeau, 64, of Crystal, typically votes Democratic but is keeping an open mind this time.

“I don’t know McFadden at all, except he’s just been on commercials I’ve seen the last few weeks,” said Barbeau, who said she’ll likely vote for Franken unless she learns more about his challenger. “I usually get stuff in the mail, but I haven’t this year. All I’ve seen is the one commercial with his son, and I thought, ‘Well, that’s not much of an election, buddy.”

Poll results show Franken topped McFadden in all age demographics except for young adults ages 18-34, where the candidates were tied at 39 percent support, while 20 percent of them remain undecided. Franken takes his biggest lead in the 50-64 age group, with 56 percent of backers compared with 32 percent for McFadden.

Respondents in the poll self-identified as 39 percent DFL or Democrat, 32 percent Republican and 29 percent Independent or other.

Franken and McFadden are nearly tied among independents with about a third each, while 25 percent of independents are undecided. There is a decided gender gap. Nearly 60 percent of women support Franken, while men favor McFadden by an 8-point margin.

HOW THE POLL WAS CONDUCTED About the poll Today’s Star Tribune Minnesota Poll findings are based on interviews conducted Sept. 8-10 with 800 Minnesota likely voters via landline (70 percent) and cellphone (30 percent). The poll was conducted by Mason-Dixon Polling and Research Inc. Results of a poll based on 800 interviews will vary by no more than 3.5 percentage points, plus or minus, from the overall population 95 times out of 100. Margins are larger for groups within the sample, such as Democrats and Republicans, and income groups. The self-identified party affiliation of the random sample is: 39 percent Democrat, 32 percent Republican and 29 percent independent or other party. Sampling error does not take into account other sources of variation inherent in public opinion surveys, such as nonresponse, question wording or context effects. In addition, news events may have affected opinions during the period the poll was taken. Readers can e-mail questions to djmcgrath@startribune.com.

Pam Welisevich, a 48-year-old science teacher from St. Paul, said she was a Franken supporter and described herself as a “hard-core Democrat.” Franken, she said, is “really down to earth” and “seems to care more about people in general.” Of all the races, she’s most interested in the U.S. Senate race, she said, because “that’s who’s representing us on the big screen. That’s who’s taking our views with them. I’m hoping they do the right thing out there.”

Paul Fritze, a 75-year-old retired schoolteacher from New Ulm, likes McFadden. He says he’s in no better financial shape in the past few years, with prices rising while his retirement income stagnates. Fritze, who says he’s incredulous that Franken was elected in the first place, said the freshman senator’s lockstep votes with Obama render him just as out of touch as the president. McFadden’s experience as an investment banker, Fritze said, could easily translate into his duties as a U.S. Senator.

“You have to work with people and make a decision based on your knowledge as to what is best,” Fritze said. “If I were to come to him to invest things, he would have to convince me that is the way to go. That makes him qualified to lead me and do what’s best for me.”