Presidential races come down to attrition, which leaves a lone standing candidate voters can most comfortably see as their leader.
On the Democratic side, only three candidates have ever actually stood. Those are Hillary Clinton, Barack Obama and, on one unsteady leg, John Edwards.
Forget the other Democrats except Bill Richardson, who is running mate material. Joe Biden makes good points, but has become a self-caricature. Chris Dodd has Peter-principled himself. Dennis Kucinich is fringe. Mike Gravel is the least serious man running, and that counts the three evolution deniers and the two or three other wing nuts in the Republican field.
On Monday evening in that instructive YouTube debate of Democratic candidates on CNN, there came a revealing, perhaps defining, moment.
Obama fell. Edwards went ahead and teetered on down. That left only one man standing. It was the woman.
It happened when candidates were asked whether they would commit to sitting down without pre-conditions for talks in the first year of their presidency with leaders of such hostile countries as Iran, Syria, North Korea, Cuba and Venezuela.
In rapid succession: Obama revealed the Achilles that tempers his considerable talents -- the over-eagerness resulting from his youth and inexperience. Clinton displayed her savvy, moderation and judgment. Edwards said "me, too" in reference to what Hillary had said, as if he were a kid brother.
Only one was presidential, and it wasn't the over-eager one or the kid brother.
Obama jumped at the question, sensing an opportunity to distinguish himself from the arrogant, insulated, undiplomatic and inept cowboy strut of the current president. He said he would gladly commit to such sit-downs with those individuals. We must talk with our enemies, he said.
Clinton, seeing fuller context in the question, said she would not commit to any such thing. She said such meetings held inside a year without good intelligence, diplomatic planning and well-established agendas could allow those enemies to use the exercises merely for anti-American propaganda. What she committed to doing instead was setting about that very kind of preparatory work for such talks, and to restore the country's good-will diplomacy that the current administration had destroyed.
Edwards said Hillary had it right. That was fair and appropriate. But he didn't have anything to say beyond that. He tried, but merely rambled to fill time about restoring America's moral authority. Something specific and substantive about the nebulous planning that Hillary had mentioned would have been, well, presidential.
So which can one most easily envision as president? The one rashly wanting to sit down with our enemies -- and, by the way, "clarifying" himself the next day? The one agreeing with Hillary about caution? Or Hillary herself, explaining the need to change Bush's way of doing things, but not do so precipitously or blindly?
It was a moment of fast-forwarded attrition, a flashed microcosm.
That's not to say Obama didn't have his moments. He's good. But, in the end, his swipe at Clinton -- saying the best time to oppose the war was before -- was not without self-infliction.
People are smart enough to figure out that it's easy for Obama to say he opposed the war at the time, since he had no authority. He was a state senator in Illinois. That serves to remind us of his inexperience.
Meantime, Hillary, perhaps not as cold and humorless as I and others have said, got off a good line. Asked about the healthiness of someone named Bush or Clinton leading the country for 28 years running, she said that wasn't good at all. She said we should not, in 2000, have put in the guy named Bush.
Look for Hillary to be the nominee, at which point the Republicans' stuff will really hit the fan.
John Brummett, an award-winning columnist for the Arkansas News Bureau in Little Rock, is author of "High Wire," a book about Bill Clinton's first year as president. His e-mail address is jbrummett@ arkansasnews.com.