Nate Silver: Are The State Polls Skewed?

538 reports:

While there are some legitimate reasons to worry that the polls could be biased against Democrats this year, this is one reason to think they could be biased toward Democrats. Indeed, while the polls have moved toward the red-leaning fundamentals in several states like Kentucky, there’s an argument the GOP is still underperforming them nationally. The generic congressional ballot currently favors Republicans by about 2 percentage points (although it’s been wildly inconsistent from survey to survey), less than the 5-point advantage that the opposition party has had on average in midterm years. This is despite the dour mood of the country and Obama’s unpopularity.

Although you should trust the polls at this point, they suggest a range of outcomes are possible. It’s plausible the polls showing a larger Republican advantage on the generic ballot (like the ABC News/Washington Post poll, which puts the GOP up 6 points) will prove correct. If so — if we wind up with a strongly Republican-leaning national environment — we’ll know fairly early Tuesday night that Republicans are going to win the Senate. They’ll probably win some states (North Carolina and New Hampshire on the Senate side, along with a number of gubernatorial races) where they slightly trail in the polls. Gardner could win by high single digits in Colorado, as could Joni Ernst in Iowa.

The FiveThirtyEight model accounts for the possibility that the polls could be biased in either direction. That they could be biased against Democrats is part of what’s keeping Democrats’ hopes alive. But they could be biased against Republicans, too. Historically, that’s been the case often than not in red states like the ones where some of the most crucial Senate races are being held.

An article well worth your time.