1 - He is outside the mainstream group think.
a. I have often said most Americans do not subscribe to the gospel of the extreme left OR the extreme right.
b. Most Americans remain centrists and jealously protective of their guaranteed inalienable rights.
2 - He is THE most liberal (and disingenuous) Senator in the country.
3 - Unanswered questions and deep doubt.
a. Occidental College records -- Not released?
b. Columbia College records -- Not released?
c. Columbia Thesis paper -- Not available?
d. Harvard College records -- Not released?
e. Selective Service Registration -- Not released?
f. Medical records -- Not released?
g. Illinois State Senate schedule -- Not available?
h. Illinois State Senate records -- Not available?
i. Certified Copy of original Birth certificate -- Not released?
j. Record of your baptism -- Not available?
4 - His "redistribution of wealth" gaff.
5 - His waffle on direct talks with real and perceived enemies.
6 - A growing concern (even among his supporters) that he will say whatever is necessary but cannot be trusted to do what he says.