The four polls taken this week in Iowa that are listed by RealClearPolitics show widely different results.  NBC/WSJ/Marist shows President Obama up by 6 percentage points — 50 to 44 percent.  Gravis Marketing shows Obama up 4 points — 49 to 45 percent.  WeAskAmerica shows Obama up 1.5 points — 48.8 to 47.3 percent.  Rasmussen Reports shows Mitt Romney up 1 point — 49 to 48 percent.  What’s one to make of this?

WeAskAmerica doesn’t list its projected turnout by party, but the other three polls do.  NBC/WSJ/Marist projects a 3-point edge in turnout for the Democrats over the Republicans (34 to 31 percent).  Gravis projects a 6-point edge in turnout for the Democrats (41 to 35 percent).  Rasmussen projects a 4-point edge in turnout the other way — for Republicans (39 to 35 percent).  That’s a double-digit difference between Gravis and Rasmussen, with NBC/WSJ/Marist being more than two-thirds of the way toward Gravis.