The bottom line for Tayoun, a veteran politician from South Philadelphia, is a prison term set by federal sentencing guidelines in the range of three to four years, with no chance of parole.
In exchange, federal prosecutors have agreed not to charge Tayoun's wife, Dolores, mother of their six children, with any wrongdoing, the sources added.
"The wife is outta there, and that's the key ingredient," one source acknowledged.
"He sees the situation," the source added. "He knows what he has to do. His family is foremost in his mind. That's where his head is."
Tayoun's guilty plea has been scheduled for Wednesday before U.S. District Judge J. William Ditter Jr.
Tayoun, who would be likely to serve any jail term in a minimum-security facility, could not be reached for comment.
His defense attorney, Frank DeSimone, who participated in the plea negotiations, declined to comment, as did the case prosecutors, Assistant U.S. Attorney Lee J. Dobkin and David M. Howard.
Tayoun was indicted on Tuesday.
While serving as a lobbyist in the mid-'80s when he was between terms on Council, Tayoun allegedly paid about $30,000 in bribes to then-City Councilman Leland Beloff and to Beloff aide Robert Rego for legislation to benefit real estate developers and others who were Tayoun's clients.
Beloff and Rego are serving jail terms after being convicted with mob boss Nicodemo Scarfo in 1987 of conspiring to extort $1 million from Willard Rouse, who was then the developer of the Penn's Landing project.
Tayoun replaced Beloff after he went to jail. Beloff had replaced Tayoun four years earlier.
Sources said that Rego, an admitted drug trafficker, had informed authorities about Tayoun's alleged bribes and would have testified against Tayoun had the case gone to trial, in hopes of getting a reduction in his eight-year prison term.
After taking office, Tayoun gave up the lobbying business but not a share of the fees clients paid to get things done in City Hall, prosecutors said.
Federal authorities said Tayoun secretly and illegally received about $20,000 from his associate lobbyist, Barbara A. Williams, or about half the fees she collected, between November 1988 and October 1989.
Ethics laws governing elected officials prohibit such arrangements.
Williams, once a close friend of Tayoun's, became an informant last year and taped him on two occasions when he asked her to lie to the grand jury to cover up their illegal fee-splitting arrangement, prosecutors said.
The tapes led to the obstruction-of-justice charges, and were the most damning evidence of all, sources said.
"You can cross-examine Bobby Rego but you can't cross-examine a tape," one source noted.