Sam Katz and John F. Street have already booked more than $2 million worth of TV and radio ads for the last two weeks of the mayor's race, easily a record for general-election media spending in Philadelphia.

"I think it's the largest amount of money that has ever been spent by two candidates over a final two weeks in any campaign in this media market, including for president, governor, Senate or Congress," said Neil Oxman, Katz's media specialist.

Spending is running at roughly $500,000 per candidate per week, nearly double the previous two weeks. Buys are ranging from early-morning news shows to late-night talk shows; from $125 for 30 seconds on Cosby reruns to $24,000 on ER.

From now until the election Nov. 2, there is only one way to avoid seeing either Katz or Street on television: Turn off your set and keep it off.

The candidates will saturate the airwaves. Both campaigns, flush with money, have dispensed with strategic buying focusing on particular target groups and demographics such as age, race or sex.

Where the campaigns had once acted more like finicky customers in a gourmet shop carefully choosing their buys - football to appeal to men, a drama like Chicago Hope to reach women - they more recently started buying everything, and in bulk.

"The time for surgical strikes is over," said David Axelrod, who produces and places ads for Street. "The candidates are now casting big and expensive nets."

Added Oxman: "We're buying everything . . . It's a very, very small group of people who are not going to see our commercials."

The spending has been competitive. Republican Katz's total airtime buys so far at the four network affiliates - NBC, ABC, CBS and Fox - total $937,000 from Oct. 19 through election eve. Democrat Street has booked $873,000 worth, according to records available at the TV stations.

The campaigns were also buying time on radio, roughly $300,000 total for the final two weeks, plus additional ad time on smaller local TV stations and cable TV.

Talks are still ongoing about additional buys. One program for which time was still available is expected to be highly rated and very expensive - baseball's World Series between the New York Yankees and the Atlanta Braves, to be aired on WCAU-TV (NBC) starting tomorrow.

The final weeks of the campaign present the last opportunity for the candidates to energize supporters and sway undecided voters.

It also is the time for what they consider their most effective commercials. Sometimes campaigns prepare a number of ads and choose which ones to air - one issue versus another, nasty or nice - at the last minute, depending on polls and the actions of adversaries.

While the campaigns will not divulge the nature of forthcoming ads, Street is expected to have at least one featuring Mayor Rendell. Rendell, in a recent interview, said he would appear in $250,000 worth of TV ads supporting Street during the last 11 days of the campaign.

Other campaigns have seen big-time spending in the Philadelphia market, including the 1994 governor's race between Republican Tom Ridge and Democrat Mark Singel, and the 1996 presidential contest. But the final two weeks of this year's mayoral election appear to exceed both.

One reason the candidates were spending so much is that they had so much to spend. Katz and Street today are due to report campaign fund-raising since shortly after the May primary, when Street defeated four Democratic opponents and Katz ran unopposed.

Street's campaign was expected to show it had raised about $4 million since that time. Katz's campaign said it would be competitive.