Charisma held hostage: Day 155.

As the Nerd of the Century mayor's race enters its final two weeks and policy wonks Sam Katz and John Street engage in perhaps their 100th electrifying debate on whether the city wage tax should be reduced to 4 percent or 4.46 percent, a city sleeps.

Trying to get excited about this mayor's race is like buying tickets to the Fight of the Century, only to discover that it's a calculator battle between two certified public accountants.

Katz is the white nerd. Street is the black nerd.

That's all we know. That's all they are going to tell us.

The white nerd doesn't want to agitate the black nerd's base. The black nerd doesn't want to agitate the white nerd's base.

So they appear almost nightly together, hum elevator music at each other - I'll give Eagles tix to the first reader who can show me a real-life difference between reducing the city wage tax to 4 percent or to 4.46 percent - until they hear the snoring start.

Then they chat amiably together like two guys in on the same joke and head home.

Are they really running for mayor in the country's fifth-largest city or for a seat on the grange somewhere in Kansas?

Anybody seen Toto? Small dog about yay-high, once pulled away the curtain to expose the alleged wizard as a con man?

It's not as if there aren't real issues here.

Street supports the Doctor of Cosmetology who superintends the city's dysfunctional public school system by applying thick layers of pancake makeup in the form of statistically hilarious test scores.

Katz wants the cosmetologist replaced with a superintendent who can actually run an urban school system - someone who, unlike the cosmetologist, has a background in, say, education instead of lip gloss.

Katz whispers this, very softly.

Street was a major supporter of the North Philadelphia empowerment zone, immortalized by a million-dollar hole at 16th Street and Cecil B. Moore Avenue that was supposed to be the Billie Holiday Entertainment Plaza but is instead a swampy pond upon whose waters no scat will ever be sung.

Katz hasn't said a word.

Street, who bills himself as Mr. Neighborhoods, delayed Project Home - permanent housing for the homeless - at 15th Street and Fairmount Avenue for two years until a federal judge forced the city to allow Sister Mary Scullion to open.

Project Home - with its resident-run afterschool programs, bookshop and restaurant - has been a pillar of the community ever since.

So Katz could question Street's posturing as Mr. Neighborhoods.

But he doesn't. And he won't.

Let us review: Katz is the white nerd. Street is the black nerd.

Only one can be Nerd of the Century. A city sleeps.