The district's African American wards were pretty united in their disdain for Fenty. It was a shocking development for the first-term black mayor, who four years ago was hailed as the antithesis to the old-style Washington politics epitomized by former Mayor Marion Barry.
In his zeal to reform D.C., Fenty brushed aside warnings from aides that black neighborhoods were complaining that he had lost touch. While Washington fared better than many cities during the recession, some black communities suffered from 30 percent unemployment and thought Fenty should be doing more.
Then, there was the ill will created by the woman he appointed to run D.C. schools. Schools Chancellor Michelle A. Rhee has been hailed nationally for beginning to turn the schools around. But she has fired hundreds of teachers and principals for poor performance, and many of them are black.
In the end, black voters decided Fenty's accomplishments weren't as important as his aloofness, when it came to them. The man who at age 34 became one of the youngest mayors of a major city was defeated Tuesday by 67-year-old D.C. Council Chairman Vincent C. Gray, who is also black.
Why should this be significant to Katz and Knox, who are white? Because they know this city's black community has never been all warm and fuzzy about Nutter. In a recent poll, only 42 percent of African Americans rated Nutter's performance as mayor as excellent or good, compared with 53 percent of white voters.
Knox and Katz know Nutter is mayor because he won a five-man primary that included two other African Americans, before easily beating a white Republican in a city that is overwhelmingly Democratic.
Knox and Katz know that in a Democratic primary next year that includes at least one other credible black candidate who can milk some of the African American antipathy toward Nutter, they might be able to glean enough of his white support to pull off an upset.
Nutter, following an example that worked well for President Obama, has steadfastly refused to be pigeonholed as a black candidate, or now, as a black mayor.
While his predecessor, John F. Street, famously declared that his election meant the "brothers and sisters" were in charge, Nutter is reluctant to make any racial distinctions in discussing his policies - be they economic, educational, or crime. It's as if he is fearful of upsetting the white liberal establishment so instrumental to his success.
But Knox and Katz are likely guessing that Nutter is also vulnerable among white liberals, many of whom have been frustrated by the lack of dynamism they thought Nutter would bring to reforming city government. It takes time to change institutions that have been steeped in cronyism and deceit for decades, but Nutter's approach does seem meek.
Take the Philadelphia Housing Authority scandal, for example. It's true that other than his authority to appoint board members (and he's late in doing that), the mayor has little to do with running the PHA. But he has failed to effectively use his bully pulpit to reassure the public that he will fight to change a PHA board that was blind to the multiple sexual-harassment accusations against PHA Executive Director Carl R. Greene.
If white voters who supported him start believing Nutter isn't the reformer that they elected, and black voters start thinking someone else might be more responsive to the specific needs of their community, then Nutter just might be successfully challenged.
Nutter gets credit for bringing in a new police commissioner, Charles H. Ramsey, who has done a credible job and is popular. But Washington Police Chief Cathy L. Lanier gets good grades on reducing crime in that city, too, and that didn't help her boss, Fenty, win his race.
Those disenchanted with Nutter include some operators of black businesses who believe they should be feeling the impact of a black mayor more than they are.
And then there are those critics, like Fenty's in D.C., who link Nutter with their disdain for this city's reform-minded schools superintendent, Arlene Ackerman. Teaching was once the most viable employment option for educated African Americans in both cities, as well as the rest of the country, so there are a lot of black teachers. Many don't like how Ackerman is shaking things up.
I doubt any of this means three-time loser Katz or solo-failure Knox can actually beat Nutter next year. If that's what Street is whispering in their ears, they need to cozy up to someone else. But the right opponent might give Nutter a run for his money, if he, like Fenty, breaks a cardinal rule for all politicians: Always pay attention to your people.
Chat live with Harold Jackson Monday at 1 p.m. on www.philly.com
E-mail Inquirer editorial page editor Harold Jackson at firstname.lastname@example.org.