The moment has arrived.

Gathered for the last time in the Great Hall of Deliberation, the Ferrick Commission is about to fulfill its solemn duty as Official Handicapper to the Race for Mayor.

The Commissioners are gathered around the table. Our motto, emblazoned on a silk banner, flutters above: Errabundi Saepe, Semper Certi (Often Wrong, But Always Certain).

We have consulted the auguries. We have cogitated, deliberated, meditated. Now, we are ready to predict. The envelope please. And the winner is. . .

Sam Katz.

Four of the six Commissioners believe the personable Republican is going to win on Tuesday. The margins predicted range from 12,000 to 20,000 votes - the equivalent of a 3- to 4-point spread. The chair believes it could be higher.

Two Commissioners dissent, albeit gently. They believe that the estimable John F. Street can still eke out a win - perhaps by several thousand votes - if the moon and the stars align in just the right way.

The three components

The Commissioners agree on the necessary components of a Street victory:

1. He must get about 94 percent or better of the votes cast by African American Democrats.

2. His organization must juice up turnout in black wards so it equals white turnout.

3. If 1 and 2 come to pass, he will still need to get a chunk of the white Democratic vote -- 18 percent might do - to become Mayor Street.

Street's problem is that if he falls short of any of these goals -- even a smidgen - the roof will fall in.

Hence the visit Friday from the chief surrogate, Bill Clinton himself. Hence the annoying calls from Hillary. Hence Ted Kennedy. These luminaries were here to mobilize the base, particularly among African Americans.

Will it create a last-minute surge in support that will put Street over the top? Most of the Commission thinks not.

Our thinking -- as enunciated by one Commissioner - goes along these lines:

"In 1987, Wilson Goode defeated Frank Rizzo by about 17,000 votes. Now, ask yourself: Is Katz a stronger candidate than Rizzo? Yes. Is Street a stronger candidate than Goode? No. So I don't give a damn what they are saying about surges."

A thousand reasons

How will it come to pass that Philadelphia elects a Republican mayor for the first time since 1947?

There are a thousand little reasons, but one big one:

Street has failed to summon forth the coalition of black, Latino and white voters needed to win. This coalition - of working-class and middle-class blacks and progressive, upper-middle-class whites - has ruled the city since 1979.

To quote one Commissioner: "The blueprint for an African American to win the mayor's office was written by Wilson Goode - the coalitions you have to put together. John Street didn't do it."

The Democrat's Achilles' heel is his base, particularly among middle-class blacks whose feelings toward Street seem to be, um, tepid.

This imperils both margin and turnout, items 1 and 2 on the Street "must" list. The Commission believes that the vast majority of African Americans who vote will come home to Street. The slippage will be slight - but significant.

As to the SWDs - the Swing White Democrats - Katz is going to win this vote. Though Street will get his share, the Commission believes it will not be what he needs.

Can he make up the loss of the progressive vote in white, ethnic wards? We think not - though efforts by party and labor may help him. So, there goes No. 3 on the list.

What are we left with? Meet Mayor Katz.

At this juncture, our duties fulfilled, we rest. We leave the field to the voters. For the final word.