Maybe she is just trying to protect her fortune.
If Kerry wins, there are four years ahead in which things could go wrong, and each time there is a potential that people would take it out on her ketchup business.
She can't publicly withdraw support for her husband, that would hurt her business too. Thus, Kerry's put her in an impossible situation.
So she publicly support's Kerry, but in a less than enthusiastic way. Hence, her stance of "Vote for Kerry, He's not qualified, but is more so than the other guy."