John F. Street used the word three times in a row yesterday to describe Sam Katz's positions on public education.

Street, the Democratic nominee for mayor in a Democratic town, clearly was sending a message that Philadelphians could not afford the risk of electing a Republican for the first time in a half-century.

With the election five weeks away and amid signs that it could be reasonably close, Street this week has been leveling the charge that Katz, as mayor, would dismantle the city schools.

The Katz camp retorted that their man's educational positions are not much different from Street's - and that Street knows it.

Street's broadsides, the Katz partisans said, are both misleading and a sign that he is growing desperate.

To find a way to pin the "radical" label on Katz, the former City Council president yesterday referred to an article last November in the Daily News that quoted the GOP nominee as saying: "One of the strategies I intend to talk about is changing the Board of Education from being a direct provider of services to being a purchaser."

Katz, a businessman, was further quoted as saying he would seek bids from people who wanted to provide education. He said these might include "charter schools, community schools, schools run by the teachers union, religious schools, for-profit schools - whoever could meet the criteria and standards."

Said Street: "Sam Katz wants to do something that is very radical and very different. He's talking about privatizing public education. . . . This is a radical, radical, radical departure from anything we have heard in the area of public education."

Bob Barnett, Katz's campaign director, said yesterday that he did not dispute the accuracy of the Katz quotes from last November.

Katz has not made such comments in his campaign this fall.

Katz does, indeed, plan to reform the schools, Barnett said. But these reforms, he said, are not all that different from what Street has said he would do.

"He's talked about small class size. He's talked about better teacher training. He's talked about better administrative structure at the school board. And on and on and on."

On educational matters, Barnett said, Street and Katz "are not miles apart, they're inches apart."

He said of Street: "This guy is distorting what we're saying."

Even their positions on school vouchers are not all that different, Barnett contended. Katz has said he is for vouchers. Street said yesterday he is against them as long as public schools are underfunded.

In three days, Street has launched three attacks on Katz in an attempt to define him as an education radical.

He has seized on public schools as what political pros call a wedge issue - a way to differentiate himself as a tried-and-true Democrat in a city where registered Democrats outnumber the Republicans, 4-1. His polls tell him that support for public schools is a traditional Democratic issue.

Ironically, Katz said this summer that vouchers could do the same for him. Vouchers, he said, appeal to working-class and middle-class people of all parties who are seeking an alternative to public schools.

Street, on Sunday, debuted a television ad that says: "As a Republican candidate for governor, Sam Katz called for a huge cut in education taxes. Katz said less money actually would improve our schools. Now Katz says we should privatize Philadelphia schools - bidding out the education of our children to contractors; through tax-financed vouchers."

The contention that Katz wanted to cut education taxes came from a 1994 press clipping dealing with Katz's bid for governor. It quoted Katz as calling for a mandated, 30 percent reduction in all school district property taxes.

Barnett said yesterday that Street was trying to "confuse the voters with phony issues."

On Monday, a Street statement repeated many of the assertions in the commercial and raised new ones.

And yesterday, after speaking with students at Temple University, Street said that one of the major differences between himself and Katz "is the fact that I have a long record of support for the public schools, including funding full-day kindergarten through the retail liquor sales tax and various other grants and other programs for the school district."

Katz, who served on the school board in the early 1980s, has not responded in kind.

"This is nothing more than John Street's dropping . . . in the polls and being desperate," Barnett said later.