U.S. Attorney Jay B. Stephens said yesterday that he would not seek a retrial of D.C. Mayor Marion Barry on 12 cocaine and perjury charges but will argue strongly to a federal judge that Barry be sent to jail for the single charge on which he was convicted.

Stephens's decision came amid concerns voiced by some community leaders that a second trial of the mayor could exacerbate racial tensions that surfaced during the first trial and have seemed to ebb in the weeks since.

The government's decision was made public in a brief hearing before U.S. District Judge Thomas Penfield Jackson. Stephens said afterward that his office decided not to retry the case because the public now has extensive evidence that Barry used drugs and lied to a federal grand jury about his knowledge of drug use by others.

"That overwhelming evidence is now a matter of public record," Stephens said. "Now the citizens of this community, as well as citizens across the country, can evaluate the truth for themselves regarding the allegations of illegal drug abuse and deception that had hung like a dark cloud over the chief executive of this city."

Stephens also said that he based his decision on the fact that Barry "likely would face little additional punishment" if he were convicted of additional charges, an obvious reference to the government's hope that Jackson will impose an unusually tough sentence for Barry's single misdemeanor conviction.

Stephens did not refer to one factor that usually is considered important by prosecutors in deciding whether to seek another trial after a mistrial: the vote count on the various charges by the jury. In the Barry case, the jurors were split almost evenly on most counts, even those for which the government believed it had offered stong evidence, according to interviews with the jurors.

Stephens hinted that he would recommend that Jackson impose a prison term when Barry is sentenced Oct. 26, 11 days before the general election in which Barry is seeking an at-large seat on the D.C. Council.

He said Jackson could "take into account the full range of conduct in imposing sentence and that that sentence could well be up to one year in prison, which we believe is an adequate basis for punishment . . . . "

Although Barry could face a "marginally greater" sentence if he were retried and convicted on additional charges, including three felony perjury counts, Stephens said Barry could receive a significant sentence for his single drug conviction.

After the hearing, Barry declined to answer questions from reporters. "Obviously, I am relieved at this phase of the legal proceedings," he said.

Barry's lawyer, R, Kenneth Mundy, declined to comment about the government's decision to drop the remaining charges. Mundy also declined to say whether Barry would appeal his conviction.

Stephens would not respond directly to questions about what sentence his office would recommend. But he indicated that Barry, as a public official, should be held to a higher standard of conduct than the typical drug offender.

"The ultimate truth will remain, that the chief executive officer of this city, charged with leading the fight against illegal drugs and violence, has himself been convicted of contributing to that human devastation," Stephens said.

Under federal law, one year is the maximum sentence Barry could receive for the drug possession charge, and it exceeds the sentence recommended for the charge under federal sentencing guidelines.

At yesterday's hearing, which took less than two minutes, Jackson turned down a government request to push forward the schedule for sentencing Barry, saying he intended to ask for a presentence report on the mayor from the U.S. Probation Office.

Assistant U.S. Attorney Judith E. Retchin argued that such a report is not needed.

Jackson told Mundy that his client has a 10 a.m. appointment today at the U.S. Probation Office as the first step in compiling that report. That appointment probably will be the first time the mayor will be required to submit to drug testing, something he has avoided until now.

Usually, defendants arrested on drug charges are required to submit to periodic drug tests while they are awaiting trial, but Jackson eliminated that requirement in Barry's case.

U.S. Probation Office officials usually require drug tests for defendants who are awaiting sentencing, especially if the defendant has been convicted of a drug charge.

Justice Department spokesman Dan Eramian said today that Attorney General Dick Thornburgh "was notified" of the rationale for Stephens's retrial decision, but "did not speak directly with Mr. Stephens." Although Stephens consulted with officials in the Justice Department's criminal division, the decision was "Mr. Stephens's to make," Eramian said.

Barry was convicted on the possession charge Aug. 10 after a nine-week trial. The charge related to testimony that he used cocaine with former civil rights colleague Doris Crenshaw at the Mayflower Hotel sometime in November 1988.

He was acquitted of one other possession charge, which centered on the government's contention that his alleged drug supplier, Lydia Pearson, delivered crack cocaine to him at his office the Frank D. Reeves Municipal Center on Sept. 7, 1988.

The jury deadlocked on three felony counts of perjury and nine misdemeanor counts of cocaine possession.

Under federal sentencing guidelines, a misdemeanor cocaine possession offense carries a range of probation to six months. Although under federal law a defendant can receive up to one year, most first-time offenders convicted on that charge get probation. Jackson could sentence Barry to the legal maximum of one year, but he would have to justify his decision in a written order, and Barry could appeal.

If Barry had been convicted of a felony perjury charge, Stephens said, he would have faced a sentencing range under the guidelines of eight to 14 months.

Staff writers Michael Isikoff and Bart Gellman contributed to this report.