often in the past, they have been successful at redefining "serious" to mean "pompous testosterone-poisoned blowhard", such that Democratic candidates who have tried to be "serious" have come across looking like Joementum GOPLite wannabes.  what they have gotten away with calling "serious" is a pompous style masking insane, reckless, arrogant, wasteful, fraudulent, abusive, tyrannical policies.  

(and when they can't question your "seriousness", they try to make you look angry &/or loony--cf. the "Dean scream" tempest in a teapot--or worse yet, feminine [oh, the horror!].)

fortunately, the voters at large are catching on to the fact that Democrats and progressives are more serious, more sane, more responsible, and generally more in line with what the public wants and needs.  

we used to let them get away with calling their arrogant pomposity "seriousness", but we must continue to make it plain that serious is as serious does.  

let them keep their pompous blowhard debate-club style; our leaders can be serious AND have a sense of compassion, decency, and humor--just like the rest of the American people.