Analysts say former Hewlett Packard CEO Carly Fiorina is giving Boxer her toughest campaign yet - but even so, Boxer currently holds a six point lead, 47 percent to 41 percent. The other 12 percent of Californians haven't made up their minds. The Democrat holds similarly narrow leads in two other polls out this week.
But the majority of Boxer and Fiorina supporters have one thing in common: they're basing their votes on the senator, not her challenger. Nearly 70 percent of Boxer supporters say their vote is more a vote for Boxer than it is against her opponent. And almost two-thirds of Fiorina backers say they're voting against Boxer more than they're voting for Fiorina. One potential reason: nearly three in 10 Californians say they haven't formed an opinion of Fiorina yet.