In the end, Brown pulled off the upset in large part because he won unaffiliated voters by a 73% to 25% margin. The senator-elect also picked up 23% of the vote from Democrats. [Our polling shows that 53% of voters in Massachusetts are Democrats, 21% Republican and 26% not affiliated with either party.]

Coakley also barely carried a usually reliable Democratic constituency. Union workers went for her by just six points, 52% to 46%.