The ads, the millions of dollars, the dozens of forums and hundreds of stops in the crowded DFL gubernatorial campaign all are aimed at a select group of primary voters.

Very select.

The winner of the Aug. 10 primary will likely need a mere 180,000 votes to survive, according to experts. One analysis shows that turnout may be so low that in a state of more than 5 million people, a nominee could be chosen with fewer than 100,000 votes -- about the population of Rochester.

"This is the logic of small numbers at this point," said Hamline University Prof. David Schultz.

Minnesota often leads the nation in November turnout, but Minnesotans seldom flock in big numbers to primaries. The new August date may depress turnout even more, coming during peak cabin season.

Factor in the lack of a presidential or U.S. Senate contest and a gubernatorial race that has yet to kindle voter passion and the numbers could quickly dwindle to one of the lowest turnouts in recent history.

But those who do show up will wield a mighty influence.

"As the electorate as a whole gets smaller, each individual group has more power in it if they come out and vote," said Andy O'Leary, DFL Party executive director.

Finding the voters

The smaller yield makes finding -- and motivating -- those elusive likely voters crucial.

"The key is, what's the inspirational message?" said Ryan Greenwood, Take Action Minnesota's political director. A coalition of liberal interest groups, Take Action supports DFL-endorsed candidate Margaret Anderson Kelliher.

The message needs to galvanize just slivers of the state's nearly 4 million voters. Judging from past elections, about 400,000 DFL voters will show up at August polling booths. Split three ways -- among Kelliher, former U.S. Sen. Mark Dayton and former House minority leader Matt Entenza -- and the "win number" becomes downright tiny.

Kelliher can rely in part on those party faithful who always vote for the endorsed candidate. She and Dayton also have ins with union voters. Both have endorsements from major labor groups, who use their own money and mechanisms to turn out their members.

"We do think that our members turn out more in primaries by a couple points more than the electorate as a whole," said Jim Niland, political director for the American Federation of State, County and Municipal Employees Council 5, which backs Dayton.

Entenza, who lacks institutional support, started big --he has spent more than $1 million on television ads alone -- to go small.

"We want to increase the number of people supporting Matt Entenza," said Dave Colling, his campaign manager. "The more of them there are, the easier it is for us to find them."

Colling thinks the primary winner will need 150,000 votes. "These are not big numbers," he said.

Schultz, of Hamline, ran the numbers and estimates that fewer than 230,000 people will vote in the DFL primary. At that level, the winner would only need between 76,000 and 114,000 votes.

One other byproduct of low turnout: Contested local elections can create hot zones of voter interest, giving certain geographies extra power.

Among them:

• Ramsey County, with a contested county attorney race and several legislative primaries. Extra turnout in the heavily DFL county will boost its importance in the governor's contest.

• The 30-square-mile stretch that includes Columbia Heights, Fridley, New Brighton and parts of Shoreview could see some action. That area makes up state Senate District 50, where embattled state Sen. Satveer Chaudhary will face off against former legislator Barb Goodwin, to whom he recently lost his endorsement.

• The counties of the Iron Range, long a DFL stronghold, are also home to habitual voters. In 2006, when the state's primary turnout was a scant 14 percent, the turnout in most Range counties was more than triple that.

Lots of unknowns

Despite all the targeting and educated calculations, even the DFL's O'Leary admits that it will be hard to say how many people will show up next month.

Past numbers may not be much of a guide, he said, and could leave campaigns "flying blind."

Then there are the optimistic few who say there could be an uptick compared to recent past elections.

"I have great faith that it's going to be up," said Kent Kaiser, a former Secretary of State staffer and communications professor at Northwestern University. Part of his counterintuitive take: People are too busy in September to vote; in August they'll have more time.

But no one is expecting jammed polls or long waits -- the largest turnout in the last 20 years was only 28 percent.

No matter what the DFL's turnout, one thing is near certain: the GOP primary turnout will likely be smaller. Tom Emmer, the Republican endorsed candidate, has no major opposition in the primary and is expected to cruise to an easy primary win. But he'll still draw votes. In recent statewide primaries, Republicans at the top of ticket still got more than 100,000 votes, opposition or no.

For really wee numbers check out the Independence Party primaries. In 2006, Peter Hutchinson won the Independence nod with fewer than 8,000 votes -- and that brought him 66 percent of the total primary votes cast.

While the DFLers may need to win over only as many folks as could fill Target Field four times over, Independence Party-endorsed candidate Tom Horner, challengers Rob Hahn and others with the tiny party might end up battling for barely enough fans to fill the Saints' Midway stadium.

"It's not a typical year," said Horner. "I don't know what the turnout will be."

Rachel E. Stassen-Berger • 651-292-0164