A new poll shows Sen. Blanche Lincoln (D-Ark.) leading state Sen. Gilbert Baker (R) 41-39 in a potential 2010 matchup.

The Research 2000 poll was conducted for the Progressive Change Campaign Committee and Democracy for America, which polled Senate Majority Leader Harry Reid (D-Nev.) recently as well. It also shows Lincoln leading businessman Curtis Coleman 43-38.

The polls are designed to push Reid and Lincoln to the left on health care reform and the public option, but they also have shown some real vulnerabilities for the two incumbents.

More than half of respondents -- 51 percent -- say Lincoln has been an ineffective senator.