That’s what Vice President Walter Mondale used to say at every stop in the closing days of the campaign. “Polls don’t vote. People vote.”

The only problem, of course, is that polls do measure people’s preferences, typically with greater accuracy in general elections than in primaries and caucuses, where it is more difficult to predict what the universe of voters will look like. So when you’re down in the polls as the election is approaching, it generally means that you’re down.

In recent days, there has been a spate of stories about so-called “biased” polls — biased against Mitt Romney.