Voters in Virginia don't like either of their choices for governor this fall, according to a new Quinnipiac University poll. Yet, former Democratic National Committee Chairman Terry McAulliffe leads state Attorney General Ken Cuccinelli by six points among likely voters.

Why? Mostly because Democrats appear poised to maintain their turnout advantage from 2012, when the exit poll showed 39 percent of voters identified as Democrats but just 32 percent as Republicans. Democrats outnumber Republicans by an identical seven-points among likely voters in the Quinnipiac survey, and both candidates win at least 90 percent of their fellow partisans. With independents splitting 42 percent for McAuliffe and 44 percent for Cuccinelli, the party identification difference is entirely responsible for McAuliffe’s current lead.

The partisan makeup of the electorate – particularly determining likely voters in an off-year election – is a moving target, and it’s unclear whether Democrats’ current wide advantage will hold on Election Day.

Virginia Democratic gubernatorial nominee Terry McAuliffe.

Democrats have consistently outnumbered Republicans among all Virginia adults in recent years, but Republicans have neutralized that advantage by turning out at higher rates in off-year elections. In the 2009 governor’s race, which was won by Republican Bob McDonnell, exit polling showed GOPers held a four percentage-point edge over Democrats only one year after Democrats’ six-point party identification edge in the 2008 presidential election.

Quinnipiac, like most public polls, does not “sample” or “oversample” a predetermined numbers of partisans to ensure it resembles past electorates. Instead, the partisan makeup is determined by a standard question: Generally speaking, do you consider yourself a Republican, and Democrat, and Independent, or what?

What’s most striking is that Democrats’ five-point party identification advantage from a July Quinnipiac poll was not diminished by the firm’s switch to likely voters this month. This indicates that Cuccinnelli is not benefitting from a narrower likely voter electorate, a factor that may make a victory hard to pull off.