Only about one-third of voters have a positive opinion of Congress -- a 13 percent decline in favorability since April, a new Pew Research Center poll finds.

That striking drop in support -- which Pew says puts Congressional favorability at its lowest in 24 years -- is doubly discouraging for Democrats, who ceded ground to their Republican counterparts in Pew's companion poll.

A look at the crosstabs reveals the drop in Congressional approval is most apparent among independent voters, only a third of whom now view Congress positively. Even Democrats are less likely to view their own majority favorably, down 10 points since April. Republicans, predictably, remain "overwhelmingly negative" of Democratic governance.

Taken together, the numbers spell bad news for the Democratic Party, which already fears important losses in 2010. Although Democrats still lead Republicans in measures of effective governance and voter empathy, the party's lead seems to have narrowed on most fronts, Pew reports. Voters are now 4 percent more likely to select a Republican in 2010 -- and 7 percent less likely to select a Democrat -- putting both parties within a point of each other in Pew's election measurement.

"At about this point four years ago, Democrats led in the generic congressional ballot by 52% to 40% and went on to win a majority of the popular vote and regain control of Congress the following November," according to the poll.

On health care, especially, Democrats have lost notable ground, as fewer than half of respondents (a 10 point drop) said the party is best equipped to handle the issue. Here, again, Congressional Democrats still fare better than their Republican counterparts -- by about 20 points -- but the numbers indicate sentiment might slowly be shifting.