Murphy has 52 percent support to West's 43 percent support, according to a poll conducted for House Majority PAC, a group working to regain a Democratic majority in the House.

West is also seen more negatively by voters in the 18th district; only 40 percent view him positively, while 47 percent have a negative view of the congressman. Murphy, however, is seen positively by 33 percent and negatively by 29 percent.

A number of polls of the district released over the past few weeks have provided different reads on the race, with an internal poll from West's campaign giving him a lead, and another GOP poll putting Murphy ahead. But this new poll oversampled Republicans by a larger margin than actually exists in the district, indicating there might be some validity to Murphy's lead.

House Majority PAC seems to believe so. The group is spending $1.5 million there and recently launched its second ad in the race, which attempts to use West's own words against him.

The poll was conducted among 401 likely voters from Sept. 26-27 and has a margin of error of 4.9 percentage points.