Perhaps the Democratic voters of Georgia will give Vernon Jones the benefit of the doubt, voting for his policies and ignoring his personality. After all, DeKalb County, where Jones has headed county government for the past 7 1/2 years, is in pretty good shape. While his personal conduct is frequently outrageous, Jones' policies are usually reasonable.

But Jones got that backward when he voted twice for George W. Bush. In last week's Atlanta Press Club debate with his runoff opponent, Jim Martin, Jones said he frequently disagreed with Bush's policies, but he voted for "the man."

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Uh-oh. If that's the standard, Jones ought to go down to flaming defeat in Tuesday's runoff. In matters of character, temperament and conduct, Jones is a disaster. If he wins the Democratic nomination for U.S. Senate, his opponent, Republican incumbent Saxby Chambliss, will use Jones' tarnished personal history to trounce him.

And that tarnish could move up the ballot to sully Barack Obama. While the Chicago senator believes he has a good shot at winning Georgia in the fall, Obama's chances depend on a good showing for Bob Barr, the Libertarian candidate for president, and a lack of enthusiasm for John McCain among the state's ultraconservative Christians.

McCain has never been an icon of the religious right, and those voters have kept him at arm's length. But that same group might turn out in large numbers to vote against Jones — which would be bad news for Obama.

Jones has tried mightily to ride Obama's coattails, claiming that he represents the same generational shift and post-racial dynamic. Jones has presented himself as similarly interested in moving beyond polarized politics. He has gone so far as to send out fliers with manipulated photographs, creating an image in which he seems to be appearing side-by-side onstage with Obama, under the heading, "Yes We Can."

But Obama wants nothing to do with Jones. "I do not endorse him. I have not endorsed him. He put my picture on his literature without asking me," the presumptive Democratic nominee told Atlanta Journal-Constitution reporter Aaron Gould Sheinin last month. Obama has only the vaguest notion of who Jones is.

Besides, Jones is, in many ways, the anti-Obama. The Illinois senator has become known for an even disposition and poise under pressure. Even under the klieg lights of high-intensity debates, he doesn't raise his voice. He doesn't have a legendary temper. He doesn't wilt under criticism.

Jones, by contrast, is mercurial, paranoid, hypersensitive to criticism and combative toward those who disagree with him. He's prone to playing the race card, asserting that many of his critics simply want to undermine a successful black man. He values loyalty over competence. (No wonder he voted for Bush twice.)

Obama is married with children, settled, traditional about family life. He has spoken frequently about parental responsibility, stressing the negative effect that absent fathers have on the lives of their kids. His wife is an accomplished professional who has also emphasized her traditional views of family life and parenthood.

Jones, on the other hand, is a bon vivant, a rakish man about town frequently seen in the company of glamorous women — often more than one at a time. Indeed, Jones was accused of rape (though never formally charged) in December 2004 after a sexual encounter with two women went bad.

Even in his professional life, Jones has a checkered history with women. In 2004, DeKalb County Commissioner Elaine Boyer filed a police report alleging that Jones shoved her in a hallway outside commission chambers after a heated dispute over a budget vote. That came shortly after a constituent claimed that Jones had been threatening and intimidating in an encounter at her home.

Martin, Jones' opponent, is a low-key fellow without much charisma, but he has a solid record of accomplishment, without the baggage that Jones drags in his wake. The last thing Democrats need on the fall ticket is a loose cannon like the DeKalb CEO.