“We’ve gone from a blue state to a purple state overnight,” said longtime Republican consultant Todd Robert Murphy. “No one knows for sure until the dust settles. But knowing Paul Ryan’s personality and how Wisconsin voters tend to be parochial, Barack Obama should be gearing up for a race.”…

When Marquette University asked questions about Ryan in a July poll, the results suggested he could make a difference. The survey found that more voters have a favorable than an unfavorable view of the congressman; the opposite is true for Romney. The starkest contrast is among those crucial independent voters. Of Ryan, 40 percent have a favorable view, while 25 percent hold an unfavorable view. Views of Romney are 31 percent favorable, 40 percent unfavorable.

“That’s the reason Ryan brings something valuable to the ticket,” said Marquette University pollster Charles Franklin. “Both of them are polarizing among Democrats and liked by the Republican base. The difference is among independents.”