Voter dissatisfaction over the government shutdown could endanger Republicans' House majority, new polling from a progressive group indicates.

A poll of 24 Republican-held swing districts shows that a generic Democrat would beat a Republican incumbent in 17 of them — the very number of seats Democrats would need to wrest from Republicans to take control of the House.

Republicans tied with the generic Democrat in two swing districts and led in five others. But all seven of those Republicans lost support once voters were told they backed the current government shutdown.

"These were the kinds of numbers we were starting to see in Democratic districts four years ago," Tom Jensen, director of Public Policy Polling, said Monday. "We did see the seeds of discontent in the summer and fall of 2009, we did see that continue through to [the midterm elections in] 2010."

Jensen said the poll was conducted to determine whether there were enough districts for Democrats to seriously challenge Republicans' grip on the House in 2014.

"This is just one tool to demonstrate [Republicans'] political vulnerability," said Brad Woodhouse, president of the progressive Americans United for Change. "They can get right with this by getting a vote on the floor for a clean CR and open up government."

The new Public Policy Polling survey was commissioned by the progressive group and conducted Oct. 2-4 with sample sizes between 600 and 700 respondents in each district.

This follows a poll conducted in August for Republican members of Congress by pollster David Winston, which showed that 71 percent of respondents opposed a government shutdown as a means to defund the Affordable Care Act.