The indispensable election numbers cruncher Jay Cost has an interesting post today, the gist of which is that: “Liberalism does not have political life outside the Democratic party.” He concludes: “Liberals might be frustrated now, but during the campaign next year the Democratic party will activate their partisan sentiments by casting the Republican nominee as the bane of all that is good, true, and noble – and the left will buy it. The same liberals who are complaining about Obama today will be earnestly proclaiming that his reelection is the only thing that stands between America and the abyss.”

I agree that it’s inconceivable solid liberals will vote for any Republican for president. But, as many conservatives did in 2008, they can certainly sit home. And they can direct their donations and volunteer efforts to congressional, senate and gubernatorial candidates. As CNN reported in 2008, “Compared to 2004, Republican turnout declined by 1.3 percentage points to 28.7 percent, while Democratic turnout increased by 2.6 points from 28.7 percent in 2004 to 31.3 percent in 2008.”

That is no doubt why, immediately after signing a debt-ceiling bill that the left hated, Obama gave a stump speech singing from the left’s hymnal (more taxes, “more investment,” etc.). He doesn’t need to fear that the left will vote for the GOP nominee; however, there is good reason to be concerned about voter turnout and donations.

I don’t mean to suggest by any of this that a candidate can win only by pumping up his base. In 2008, Obama won independents and enjoyed a huge Democratic wave of enthusiasm. This time around, polling shows that independents are showing a preference for Republicans and for conservative economic policies. Obama’s task then is to engage the left and to reach out to independents. That was much easier in 2008 when he was an unknown quantity. It’ll be much trickier this time around.