Poll after poll after poll shows the same thing:
Americans hate Congress.
Approval ratings in the mid-teens, disapproval ratings in the high 70s, there are few institutions folks hate more than Congress.
And Paul Ryan is one of the "leading lights" of Congress, and I think more folks will go sour on Paul Ryan simply based on the idea that they will rightfully associate him with an ineffectual partisan Congress that rarely seems to have the America's best interests at heart. While it is true that people like their Congressperson and folks in Wisconsin's First District like Ryan, he is now a National candidate.
He is a Tea Partier's dream, but for the crucial undecided middle they are going to have a poor opinion without knowing more than he is a member of a group they hate, and as they learn more it is highly unlikely he will gain their trust. Romney should have stayed far away from anybody in Congress, but he didn't... because he is an idiot.