An intriguing late development in Minnesota’s governor’s race:

In the governor’s race, incumbent Democrat Mark Dayton still leads Republican Jeff Johnson 47 percent to 42 percent. Hannah Nicollet of the Independence Party is at 2 percent tied with Libertarian candidate Chris Holbrook. Another 6 percent are either undecided or support other candidates. Dayton [led] by 12 points a month ago and five points two weeks ago.
“Independents often swing elections and Mark Dayton had a lead among independents and that lead is now gone,” says Larry Jacobs of the University of Minnesota Humphrey Institute after reviewing our survey data. Independents are often a volatile block of voters. Two weeks ago Dayton led Johnson by six points among independents. Now he trails by 12.

In this cycle we’ve seen a few states where Democrats traditionally win by modest margins — New Mexico, Oregon, and Minnesota — in which early polling showed incumbent Democrats ahead by giant margins . . . and then slowly saw that lead revert to its traditional closer margin. In New Mexico’s Senate race, Allen Weh is getting closer, but still trails outside the margin of error. In Oregon, gubernatorial candidate Dennis Richardson is also trailing in the recent polls by just outside the margin of error, after trailing by double digits earlier.

In Minnesota, Dayton won in 2010 by four-tenths of a percentage point. In 2006, Republican governor Tim Pawlenty won reelection by a percentage point. So earlier polls showing Dayton winning by 10 to 12 points indicated a big change from usually hard-fought, closely contested elections. (Recall in 2008, Al Franken won the Senate race by 228 votes after a lengthy legal battle and questions about convicted felons voting illegally.)

Making up a 5-point deficit in the final day is a tall order for any candidate. But we shouldn’t be surprised to see a Minnesota result much closer than the polling of spring and summer indicated.