Markey released internal polling numbers showing her leading Musgrave, 43 to 36 percent. The poll showed only 30 percent of districtwide voters wanting to re-elect Musgrave, while 38 percent said that they would vote to replace her.
Only 40 percent approve of her performance in Congress, while 51percent gave her negative job rating.
The poll was conducted by the Democratic firm Bennett, Petts and Normington, surveyed 400 likely voters between May 13-15.
In response to the poll, Musgrave released her own internal polling from March showing her leading Markey, 47 to 42 percent. Still for an incumbent, Musgrave's sub-50 percent total from her own polling is a serious warning sign for the November general election.
Musgrave had the lowest winning percentages for any winning incumbent last election cycle, taking only 46 percent of the vote in a three-way race against Democrat Angie Paccione and independent Eric Eidsness. The Fort Collins-area district, though, still favors Republicans: President Bush won 58 percent of the vote there in 2004.