Wisconsin residents once brimmed with stories of bipartisan cooperation — or at least civilized discourse between opposing political sides. Overflowing here now: stories of marriages, friendships, workplaces, Thanksgiving dinners divided by the fight that began in February 2011, when Mr. Walker announced plans to cut benefits and strip collective bargaining rights for most public workers.

Winning this election may be less a matter of convincing undecided voters, if there are any, than of getting people to the polls. The splintering that started when Mr. Walker cut bargaining rights has seeped into other issues: austere budget choices; a voter ID law; removal of a law that allowed people to seek punitive and compensatory damages in state court over employment discrimination; efforts to encourage iron ore mining,

Among the voters, the sides are stark and, more than a year after tens of thousands of protesters marched around the State Capitol in Madison, surprisingly raw.

“We don’t want the state taken over by the Koch brothers,” said Mary Jean Nicholls, a former teacher, referring to Charles and David Koch, billionaire industrialists who are among Mr. Walker’s supporters.