Some in the liberal commentariat have opined that conservative voters are rallying to Cain because he is black. Maybe so. But most seem to back him because he seems conservative, articulate and likeable.
We don't have any significant polling to tell us whether the Politico story has cost Cain support. My hunch is that it hasn't -- at least not yet.
But that leaves the possibility that his support may evaporate when voters have to decide for real. Pollsters ask respondents whom they would vote for "if the election were held today." But one thing everyone knows is that it isn't being held today.
That won't be true when Iowa Republicans venture into precincts caucuses on Jan. 3, the ninth day of Christmas, which is the first real voting day, as it was four years ago.
Then they may respond as members of a Midwestern focus group did a couple of weeks ago, when pollster Peter Hart asked them to raise their hands if they thought Cain was prepared to be president. No one did; not even those who had been saying positive things about Cain.
We can get some sense of who voters think is prepared for the job from the weekly polls on general election preference conducted by Scott Rasmussen.
He finds that a generic Republican leads Barack Obama by a 47 percent to 42 percent margin. Obama's 42 percent tracks pretty well with his job approval in Rasmussen and other polls.
Rasmussen finds that Mitt Romney runs 3 points behind the generic Republican and 2 points ahead of Obama. He's the only Republican running ahead.
Cain and Perry run 9 points behind the generic Republican in Rasmussen's polls. Other candidates run 12 to 15 points behind.
Cain has been leading or tied for the lead for most of a month now, and he may hold that position for a while. But will his lead hold when voters vote for real?