MANKATO – This midterm election, the DFL Party is not just worried about Republicans — it's worried about DFLers.

With less than a week until Election Day, Minnesota DFLers are launching a six-day bus tour across the state in a final sprint to clinch voters who often skip some elections: college students, blacks, Hispanics and new immigrants.

These voters, who tend to vote DFL, often turn out in droves during presidential election years, but tend to sit out midterm elections.

"Drop-off is our biggest enemy," said party chair Ken Martin. "Our enemy this year is not the Republicans; it's really Democrats. If they drop off like they did in 2010, we're going to lose."

A Star Tribune analysis of voter-turnout data found that in more than 30 state House districts, the drop-off rate from the 2008 election cycle to 2010 ranged from 28.5 percent to 42.3 percent. Among those is House District 19B in Mankato, represented by outgoing DFL Rep. Kathy Brynaert.

DFL politicians, party and union activists are crisscrossing Minnesota, hitting party strongholds such as Minneapolis, St. Paul and Duluth in a final push to rally the base and its network of volunteers.

Mankato — with its large student population that includes more than 15,000 enrolled at Minnesota State University, Mankato — was among the first stops of the get-out-the-vote bus tour.

The chartered bus stopped Wednesday outside the union hall of the International Union of Operating Engineers, Local 49, in a largely industrial part of the city.

Martin was joined on a small stage by other DFL candidates, including State Auditor Rebecca Otto, who is running for re-election, and state Sen. Steve Simon, who is running for secretary of state in a close race against Republican Dan Severson. The candidates took turns addressing a crowd of about 60 supporters.

When Otto spoke, she made the rally message short and clear: "We don't want little margins," she said. "We want BIG margins."

Dan Conner, 69, a retired government employee and a Mankato resident, said he thinks this election cycle is critical for DFLers.

Conner, a phone volunteer for the party, worries that if Republicans take back the House majority or win the governor's office, Minnesota's economy could worsen.

"I think it's our obligation to get out the vote," Conner said. "Look at Kansas and Wisconsin — they've gone downhill. … Minnesota is on a roll."

Republican incumbents in those states are in closely watched, competitive races. Critics say that if Wisconsin Gov. Scott Walker and Gov. Sam Brownback of Kansas lose their races, it will demonstrate that they shifted government policies too far to the right.

In Minnesota, the DFL has been working since last year with community organizers and other party affiliates to communicate with college students, minority groups and new immigrants, Martin said.

And the party is tailoring its approach. For college students, for instance, DFLers talk about the cost of attending college and rising student loan debt. For new immigrants, such as those from Somalia, conversations center on education and housing, Martin said.

DFLers aren't the only groups focusing on get-out-the vote efforts. Minnesota Republicans are doing the same, albeit on a smaller scale.

The state Republican Party isn't mounting a similar bus tour, but it has a network of 18 field offices with 23 paid staffers as it focuses on its ground game.

Keith Downey, state GOP chairman, said Tuesday that his party's candidates will be canvassing the state in coming days and making some joint appearances with legislative candidates.

The Star Tribune analysis of voter turnout found that voter drop-off affects DFLers more than Republicans. Of the 32 House districts with the biggest drop in votes from 2008 to 2010, more than two dozen are held by DFLers.

Nineteen of those are safe districts for DFLers, which means that even during low-turnout election cycles, DFL legislators are more than likely to retain their seats. The drawback for the DFL is that means there are still fewer votes cast for statewide candidates, such as those for governor or state auditor.

Gov. Mark Dayton, who attended the kickoff of the bus tour at the State Capitol in St. Paul, said he hopes the get-out-the-vote efforts will pay off.

"There's always a falloff in a nonpresidential election," Dayton said Wednesday. "But we're working very hard. I know that all the groups that support us are working very hard, the DFL Party's working very hard, all the candidates, everybody. I'm optimistic that we're going to get a good turnout."

Star Tribune staff writers Glenn Howatt and Patrick Condon contributed to this report.

Ricardo Lopez • 651-925-5044