After being read positive statements about both candidates, voters give the mostly unknown Obermueller a 44 percent to 38 percent edge.

Those results show that Kline could theoretically be vulnerable in a district President Obama narrowly won in both 2008 and 2012, though partisan polls should always be taken with a grain of salt, and a double-digit initial lead is hard to overcome.

Democrats are hopeful they'll be able to make the race competitive, though Obermueller will need to show some a lot more fight than he did when Kline beat him by 8 percentage points in 2012. Obermueller raised less than $700,00 for the entire election cycle.

"John Kline should be quaking in his boots," House Majority PAC Communications Director Andy Stone. "Minnesotans know John Kline's part of the problem in Washington as he stands in the way, instead of working to find the solutions that will level the playing field for the middle class and small businesses."

Kline's campaign pushed back on Stone's comments.

"It'ss not surprising Washington Democrats are promoting their own partisan poll to gloss over the clear lack of confidence Minnesota Democrats have in Mike Obermueller, evidenced by two former Obermueller campaign volunteers announcing they're challenging him for the DFL endorsement," said Kline spokesman Troy Young. "What does it say about Mike Obermueller when his own supporters and close friends are jumping ship and campaigning against him?"

The poll of 400 likely 2014 voters was conducted by Victoria Strategies from July 17-21 and has a margin of error of plus or minus 4.9 percentage points.

This post was updated at 3:10 p.m.