Makeup of electorate weighs heavy on polls

With the two polls released Thursday, a new round of hand-wringing is taking place over the state of play in the 2010 governor’s race. The two polls — one from Minnesota Public Radio and the Humphrey Institute and another from KSTP and SurveyUSA — almost appear to be surveying different races. In MPR’s telling, DFLer Mark Dayton has a 12-point lead over Republican Tom Emmer. In KSTP’s, Dayton has a one-point lead, a virtual tie.

There’s no shortage of differences among the two polls. For starters, Humphrey is ranked near the bottom of reliable pollsters by New York Times election guru Nate Silver. SurveyUSA, meanwhile, is consistently near the top.

But there’s one stark difference in the results that will likely be the key to Tuesday’s vote: the makeup of the electorate. In the MPR poll, DFLers had a 7-point advantage in the makeup of the electorate. In SurveyUSA, the spread was plus two for Republicans. The disparate top line results can almost solely be laid at the feet of these two key differences. The question, then, is what things will look like on Tuesday.

Minnesota’s traditional DFL-favorable leanings are no secret, but at the same time 2010 is expected to be a particularly strong year when it comes to Republican turnout. A look at more recent elections can provide a window into what might happen on Tuesday.

In the last three election cycles, the state electorate has been overwhelmingly pro-DFL, said Steven Schier, a Carleton College political science professor. In 2004, it was plus three; in 2006, plus four; and in 2008, plus four as well. There are two things to be gleaned from this, Schier said: One, the Humphrey poll vastly oversampled Democrats — “plus seven is out of bounds,” he said. And two, that plus three or four is likely a high-water mark for the DFL in terms of voter turnout.

On the other hand, Schier says, the inherent pro-DFL makeup of the state electorate means reaching a plus two Republican turnout will be an uphill climb to say the least. While that’s consistent with national trends, and “within the realm of possibility,” Schier says, “it’s got to be an unusually strong Republican turnout” for Emmer to win. Without that happening, he added, the path to victory for Emmer is difficult. “He needs a stronger Republican turnout than we’ve had since 2004, probably since 2002,” Schier said.

In short, if recent history holds and the DFL maintains the edge in the overall electorate, that bodes well for Dayton. On the other hand, if it’s tied or swinging toward Republicans, Schier concluded, “then we got a real barn-burner.”