Not to be a wet blanket after yesterday’s great special election victory, but the latest Pew Research Center poll should set off some alarm bells at the DCCC and DSCC:

Americans are extremely displeased with Congress, and there are already some signs that this could take a toll on the Democrats in the 2010 midterm elections. Currently, 37% express a favorable opinion of Congress, while 52% hold an unfavorable view. Positive opinions of Congress have declined by 13 points since April and are now at one of their lowest points in more than two decades of Pew Research Center surveys.

At the same time, intentions to vote Democratic in the next midterm election are markedly lower than they have been over the past four years. Voters are about evenly divided when asked how they would vote if the election for Congress were being held today: 45% say they would vote for a Democratic candidate in their district, or lean Democratic, while 44% say they would vote for a Republican or lean Republican. 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.

Meanwhile, the Research 2000 polling for Daily Kos finds the Democratic lead on the generic Congressional ballot down to 6 points, with Democratic intensity “lagging badly”:

With Independents potentially sitting this next election out (as the numbers hint at), we’re in bad shape in a base election. Core Republicans are engaged and solidly home. Democratic constituencies are wavering (look at those African American numbers). The only key Democratic constituency to have moved more Democratic are young voters — from +30 Democratic to +37, but only because they are abandoning Republicans at a bigger rate than Democrats. And even those gains are threatened by the (non) geniuses in DC seriously contemplating a health care mandate without cost controls (like the public option).

At current rates, any 2010 losses would not stem from any resurgence in conservative ideology — Republicans are simply not making any significant gains anywhere — but in a loss of confidence in Democrats. There’s a way to change that dynamic — deliver on the promises made the last two election cycles. Failure to do that would make cynics out of too many idealistic political newcomers, while turning off base activists who do the hard on-the-ground work of winning elections.

But why deliver on campaign promises when President Obama can score points with the Beltway wizards by backing away from a strong public health insurance option?

I’m not saying next year’s elections will be determined solely by whether the Democrats deliver on health care reform. The condition of the economy will obviously play an important role too. But Obama has less control over the economic recovery than he has over whether he sells out the Democratic base. The correct choice is clear, especially when you consider that a stronger public health insurance option would make it easier to pass the bill through the budget reconciliation process in the Senate.