Actually, the Wisconsin exit polls may indicate the exact opposite, as Obama continued to make progress among several key demographic groups. This is potentially very bad news for Hillary.

Clinton's strategy in Ohio and Texas is based on winning working class white voters and women, but in Wisconsin, Obama won whites 52-46, those without a college degree 54-45, and those with an income of less than $50,000 by 53-46. Among women, Clinton's edge was just 51-48. Obama also won among every age group other than those over 60.

As far as I can tell, if these polls are accurate and indicative of national trends, Hillary's base has now narrowed to elderly democrat white women.