ST. PAUL, Minn. (WCCO) – Democrats in the U.S. House think they can win the 2nd District seat held by six-term Republican Congressman John Kline.

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But Kline has proved to be an unusually resilient congressman. Winning the seat is a lot easier said than done.

Kline once won an election by as many as 23-percentage points, and he’s chairman of the powerful House Education and Labor Committee.

But one event this summer changed the political dynamics.

House Democrats led by Nancy Pelosi had focused on GOP Congresswoman Michele Bachmann, until she abruptly dropped out of the race.

And that’s when Kline became a target.

Andy Stone, communications director for House Majority PAC, says Kline’s district is a major focal point.

“There’s no question. This district is a priority district for House Majority PAC. It’s one that Democrats believe is winnable. And we will be there to the bitter end,” Stone said.

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Republican Kline won re-election in 2012 by 8-percentage points – his narrowest victory in a decade. But considering it’s a district President Obama and Democrats easily won, Kline still made a strong showing.

But according to Humphrey Institute Professor Larry Jacobs, his southern Twin Cities suburban district is trending blue, and Democrats see an opening

“Democrats see some other opportunities either for 2014 coming up or for the next election. They see Kline’s hold on the 2nd District as growing more tenuous,” Jacobs said.

Kline declined comment, but his spokesman Troy Young says he’s fulfilling a promise to pass a new federal student loan bill before July 1.

“While Nancy Pelosi’s SuperPAC continues to play petty and partisan games with our children’s future, Kline is true to his principles,” Young said.

In the race against Kline, Democrats already have former State Representative Mike Obermuller as a candidate. Obermuller already squared off against Kline in 2012.

Even with a targeted race like this one, it’s always a longshot to defeat a powerful incumbent like Kline. And 17 months before election day, House Majority PAC already spent $50,000 on radio ads, and is going to pour more money into an anti-Kline campaign.

This is the same PAC that spent $1.5 million in Minnesota’s 8th District to unseat Republican Chip Craavack.

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It’s forcing Kline to raise and spend more money.