Will Liberals Really Stay At Home?

In the wake of the proposed tax cut deal, Nate Silver wonders how Obama's base will react:

[J]ust because liberals are disappointed with Mr. Obama does not necessarily mean they will fail to turn out and vote for him when the only other choice is a Republican. In some ways, it probably helps Mr. Obama that the country has become so polarized and that liberals view Republicans as such an unacceptable alternative, and vice versa. The prospect of a President Palin or a President Gingrich would surely motivate most liberals to vote — and even comparatively moderate Republican candidates like Mitt Romney will be under pressure to show their conservative stripes during the Republican primaries and are likely to campaign on policies, like a repeal of the health care bill, that liberals overwhelmingly object to.