U.S. Attorney Jay B. Stephens is expected to decide by tomorrow whether he will seek to retry D.C. Mayor Marion Barry on drug and perjury charges, and sources said last week it is probably the most difficult decision facing prosecutors since the beginning of their investigation.

Even if Stephens decides not to try Barry again, the sources said, he is likely to ask a federal judge to send Barry to jail for the one misdemeanor drug possession charge on which the jury found him guilty.

These sources said that Stephens would very much like to secure additional convictions against the mayor, but that as a practical matter, he could decide to ask for dismissal of the 12 remaining counts on which a federal jury deadlocked last month after a nine-week trial.

Stephens has declined to comment on the case, which is scheduled for a status hearing tomorrow, but sources familiar with it said the chance of a retrial may have decreased since Sharon Pratt Dixon won Tuesday's Democratic mayoral primary with a vow to "clean house" at city hall. Prosecutors could be concerned about the likely criticism that they were taking the city backward at a time when it had voted to move ahead, these sources said.

Barry's attorney, R. Kenneth Mundy, said he had not been told by prosecutors whether they would seek another trial.

At the outset, there were many people within the U.S. Attorney's Office, the D.C. police department and the FBI who would have liked another chance to obtain more convictions, sources said. Law enforcement officials thought that additional convictions would vindicate what they believed was a persuasive case against the District's top public official.

But, in making the decision, Stephens also must factor in the significant hurdles that would lie ahead.

First is that the government would be dealing with a jury pool just as likely as the first to contain die-hard Barry supporters or people who disapprove of the government's case. The original jury reached a deadlock on 12 counts in a 14-count indictment, with some jurors expressing open political support for Barry in the jury room. The deadlock brought a mistrial on those counts. The jury found him guilty on one possession charge and acquitted him on another.

Additionally, sources said that it could be more difficult for prosecutors to count on the cooperation at a second trial of all of the witnesses who testified against Barry at the first.

Former Barry girlfriend Hazel Diane "Rasheeda" Moore is a participant in the federal government's witness protection program and thus would have little choice but to testify again. However, Stephens may have lost some leverage last month over his other key witness, former D.C. government employee Charles Lewis, when a federal judge in the Virgin Islands placed Lewis on probation, thereby eliminating Lewis's risk of spending more time in jail for his drug conviction in the islands.

Most of all, Stephens is facing political headwinds in a city that on Tuesday gave every indication of being tired of Barry, in both his political role as mayor and his legal role as defendant.

Barry said as much on Tuesday night, speaking as a political commentator on WRC-TV (Channel 4).

"Certainly my case has been an example of what some people are very tired of, and I think Sharon Pratt Dixon represented drastic change," he said.

According to sources, including several who have talked with Stephens about the case, the U.S. attorney would like to seek a retrial but has been grappling mightily with the decision. The subject has been vigorously debated within the office. The sources said they could not rule out the possibility that Stephens could reach a last-minute decision to seek a retrial, but they said the odds are against it.

Prosecutors still see the legal case against Barry as a strong one, the sources said. The routine prosecutorial decision after a mistrial -- particularly when the government thinks its evidence is strong -- is to seek a retrial.

Some of the scenarios that have reportedly been considered by Stephens include the possibility of bringing a cocaine conspiracy case in either Maryland or Virginia -- jurisdictions where, according to trial testimony, Barry also is alleged to have possessed cocaine.

Another scenario has been to seek a retrial on only some of the 12 remaining counts, either a shortened list of misdemeanor cocaine possession and felony perjury charges or the three perjury charges by themselves.

Another argument against a decision to seek a retrial, however, is one practical factor: If sending the mayor to jail for some brief period of time is his objective, Stephens can get what he wants by pressing for a stiff sentence on the one misdemeanor possession count.

Under federal sentencing rules, a first-time cocaine possession offense such as Barry's would not usually result in a jail sentence. But those same rules give U.S. District Judge Thomas Penfield Jackson the authority to send Barry to jail or a federal halfway house for as long as six months, with virtually no grounds on which to appeal. In addition, the judge could place other restrictions on Barry's freedom, such as an order that the mayor spend each weekend in jail for the next six months.

The judge also could depart from federal sentencing guidelines and send Barry to jail for as long as a year, although Barry would have the legal right to appeal any sentence of longer than six months.

Finally, the judge is allowed to take into account evidence presented on the 12 counts on which the jury deadlocked, a factor that could significantly increase Barry's chances of a jail term.

The possibility of jail may be more than theoretical. Sources close to the case say that the mayor's actions immediately after the verdict was announced Aug. 10 served to anger the judge and may have given Jackson the rationale he needs to hand down a harsher-than-usual sentence.

Jackson, according to sources, was irritated by Barry's conduct the next day, when he held a triumphal rally at the Frank D. Reeves Municipal Center and cast the jury's mixed verdict as a vindication. Jackson also reportedly was not pleased by Barry's decision to run for an at-large seat on the D.C. Council.

In addition, the judge is said to feel that despite Barry's frequent allusions to being a recovering alcoholic, he has never taken responsibility for the drug use that Mundy, his attorney, admitted on his behalf in court. In sentencing, Jackson could take notice that Barry had not indicated any remorse for the crime of which he was convicted.

Going to jail in itself poses no obstacle to Barry's holding a seat on the council, according to Acting Corporation Counsel Herbert O. Reid, because under District law the only disqualification to holding office is a felony conviction.

"He could set up office in jail," Reid said. "He would not be establishing a precedent in this country." But, Reid added, referring to the Nov. 6 general election, "I hope the prosecutor and the judge will let some things run by themselves."

The voters' verdict remains to be seen. But as Barry conducts the campaign, he faces a dilemma: Conducting a low-profile campaign could increase his chances of losing the election, but running a high-profile one could risk angering the judge who has the power to send him to jail.

For Barry's part, the mayor could possibly head off a move by Stephens to press for a prison sentence by taking the surprise step of pleading guilty to one or more of the deadlocked misdemeanor counts. By admitting guilt on one or more of them, Barry could show the remorse that Stephens likely will argue the mayor has failed to exhibit.

According to several criminal lawyers interviewed for this article, the judge would be required to take Barry's remorse into account in deciding his sentence. And, they said, it would become much more difficult to send Barry to jail.