The dems can't forced anything. Their nominee is on the record, quoted for attribution, referring to a sitting Presidents foreign policy as "all f453ed up."
Bush was elected President after calling one of the vaunted media members, and I do mean member, a "major league asshole". Neither Bush's nor Cheneys words were for attribution, Kerrys were.
There are many who won't vote for Kerry because of his coarse language. One I know personally is a Dem, and changed her mind about Kerry when I told her about Kerry's gutter mouth.