The New York Times today was moved to ask the question that has bounced around this website for months: why is Michael Nutter, who in many ways seems to have an affinity for Barack Obama (cross-party appeal, plausible and powerful invocations of change and reform) supporting Hillary Clinton instead?

In some ways, the question that the endorsement has raised is the Rubik’s Cube at the core of the “post racial” politics that both he and Mr. Obama represent: If Mr. Obama’s candidacy is a historic racial benchmark, how do you introduce that idea into political discourse without reference to the old racial politics that give the benchmark its meaning?

Vivian McCabe, a grandmother, neighborhood block captain and supporter of both Mr. Nutter and Mr. Obama, expressed the frustration in a sidewalk interview the other day. “I was shocked,” she said, referring to Mr. Nutter’s endorsement of Mrs. Clinton. “Not because he’s black, but — I was just looking at him to...” She paused. “What words should I use?” she said. She could not come up with any.

If Mr. Nutter is inclined to ponder the conundrum, the political veteran in him — he was a Democratic committeeman, party ward leader and city councilman before running for mayor — does not show it.

The last sentence probably nails it. There's a cute section where Michael Nutter notes (over grilled cheese and chocolate milk at Little Pete's) that Obama is "'a really nice guy who’s talking about really important issues,' 'and I am aware that he is African-American.'" And an 82-year-old from Nutter's ward gets the last word: "'Nutter’s a smart fellow,' he said. 'He knows what he’s doing.' In this particular case...the new mayor just happened to be wrong."