Tom Emmer trails Mark Dayton by 1% in KUSA/SurveyUSA poll

Why the glaring gap between pollsters?

Talk about whiplash. Three polls this past week have given Democrat Mark Dayton a solid lead in the governor's race. But a KSTP/SurveyUSA poll released late yesterday shows Republican Tom Emmer within a single percentage point of his rival.

SurveyUSA says the results mean the race is now a toss-up -- at least between the Democrat and the Republican; IPer Tom Horner trails far behind them both.

And the polling firm points out that while Emmer has never led in its survey over the past few months, he appears to have closed the gap.

• Mark Dayton: 39 percent
• Tom Emmer: 38 percent
• Tom Horner: 13 percent

Yet this week, the MPR/Humphrey Institute poll gave Dayton a 12 percentage point lead. St. Cloud State University had him by 10 percentage points, and the Star Tribune gave him a 7 percentage point advantage.

Why the glaring gap between SurveyUSA and the others? The New York Times' polling analyst Nate Silver attributes the phenomenon at least in part to what he calls the "house effect" of automated telephone robopolling used by companies such as SurveyUSA; most tend to lean Republican. (Full analysis here.)

For instance, it's about 2 points for Rasmussen Reports (our estimate for Rasmussen includes polls conducted by its subsidiary, Pulse Opinion Research) and 4 points for SurveyUSA.

Here's Silver's chart:

Via NYT

That doesn't mean the SurveyUSA poll is inaccurate, however. Silver gives it a generally pretty high rating.

The only poll that really counts, of course, is the one on Election Day, just four days from now.

Previous Polls:

Oct. 28: MPR/Humphrey Institute

• Dayton: 41 percent
• Emmer: 29 percent
• Horner: 11 percent

St. Cloud State University, Oct. 25

• Dayton 40 percent
• Emmer 30 percent
• Horner 19 percent

Star Tribune, Oct. 23

• Dayton 41 percent
• Emmer 34 percent
• Horner 13 percent

Rasmussen, Oct. 22

• Dayton 44 percent
• Emmer 41 percent
• Horner 10 percent

KSTP/Survey USA, Oct. 15

• Dayton: 42 percent
• Emmer: 37 percent
• Horner: 14 percent

Rasmussen, Oct. 8

• Dayton 40 percent
• Emmer 38 percent
• Horner 15 percent

MPR/Humphrey Institute, Sept. 29

• Dayton 38 percent
• Emmer 27 percent
• Horner 16 percent

Star Tribune, Sept. 26

• Dayton 39 percent
• Emmer 30 percent
• Horner 18 percent

Rasmussen, Sept. 24

• Emmer 42 percent
• Dayton 41 percent
• Horner 9 percent

KSTP/SurveyUSA, Sept. 15

• Dayton 38 percent
• Emmer 36 percent
• Horner 18 percent

MPR/Humphrey Institute, Aug. 31

• Dayton 34 percent
• Emmer 34 percent
• Horner, 13 percent

The following polls took place before the nominating conventions:

KSTP/SurveyUSA, Aug. 5

• Dayton 46 percent, Emmer 32 percent, Horner 9 percent
• Kelliher 39 percent, Emmer 33 percent, Horner 12 percent
• Entenza 38 percent, Emmer 33 percent, Horner 12 percent

Star Tribune, Aug 1:

• Dayton 40 percent, Emmer 30 percent, Horner 13 percent
• Kelliher 38 percent, Emmer 29 percent, Horner 13 percent
• Entenza 36 percent, Emmer 31 percent, Horner 15 percent

Fox 9/Rasmussen, July 19:

• Dayton 40 percent, Emmer 36 percent, Horner 10 percent
• Kelliher 40 percent, Emmer 35 percent, Horner 11 percent
• Entenza 37 percent, Emmer 36 percent, Horner 12 percent

Decision Resources, June 8:

• Dayton 40 percent, Emmer 28 percent, Horner 18 percent
• Kelliher 38 percent, Emmer 28 percent, Horner 17 percent
• Entenza 34 percent, Emmer 27 percent, Horner 19 percent