Mayor Marion Barry, edging toward a possible bid for an at-large D.C. Council seat, appears intent on preserving enough power to safeguard his financial security and perhaps open a new chapter in his stormy political career.

Barry, who associates say will take an initial step today toward a council campaign, urged reporters outside Tenth Street Baptist Church in Northwest Washington yesterday to "stay tuned" to his political activities. Sources said he will change his party affiliation from Democrat to independent by today's midnight deadline and later take out petition forms to have his name placed on the November ballot.

Having skipped the deadline last month for running in any Democratic primary in September, registering as an independent is the first move necessary for a possible fall candidacy outside the political party that has been an important part of Barry's base for more than 16 years.

From the post of at-large council member, a skillful politician such as Barry could be both an important ally and an irritating goad inside the council and in its relations with the next mayor.

Barry, 54, who has spent his career in the civil rights movement and government, needs four more years of government service to secure full pension benefits. Some Democrats, daunted by the prospect of his holding elective office for four more years, said the mayor might be persuaded not to run if special legislation were crafted by the end of the year to preserve his pension.

With some of his citywide organization still intact, Barry is widely viewed as capable of mounting a serious candidacy for the council, where he served for four years before becoming mayor in 1978.

Although his image was tarnished by his Jan. 18 drug arrest and prosecution testimony during his drug and perjury trial, Barry could muster enough votes to split the field of candidates and capture one of two at-large seats that are up for election this fall, according to Democratic Party activists.

The at-large seats up for election are those held by Hilda H.M. Mason of the Statehood Party and Betty Ann Kane, a Democrat who is quitting to run for D.C. delegate to Congress. The seats will go to the two top vote-getters in the general election.

Mason is unopposed in the Statehood Party primary, and there are three candidates in the Democratic primary: school board member Linda Cropp, former congressional aide Johnny Barnes and housing activist Terry Lynch. W. Cardell Shelton is running unopposed in the Republican primary.

Several independents also are running, including Georgetown activist Ray Browne, Ward 2 Advisory Neighborhood Commissioner Clarene Martin and Whitman-Walker Clinic official Jim Harvey.

Mayoral candidate John Ray, an at-large council member, said a critical question is how Barry would relate to John A. Wilson, a veteran council member and longtime friend of the mayor's from the civil rights movement who is favored to be elected the next council chairman.

"Obviously, you're talking about two strong-willed individuals," Ray said. But he added, "There's a relationship there, and I think a friendship."

Ray said Barry could be quite influential on the council. "The mayor would have a great deal of knowledge, and would have at his disposal a great deal of information that the average council member does not have," he said. "I think it is very difficult to know how this would play out."

Council member Jim Nathanson (D-Ward 3) said he doubted that Barry would play a unique role on council.

"He would be one of 13 votes," Nathanson said. "It will probably be more of an adjustment for him than for the council."

Today is the deadline for registering to vote in the Sept. 11 primaries that will decide the Democratic and Republican nominees for mayor, six council seats, including the chairmanship and the two at-large positions, the city's congressional delegate and the new shadow seats in the U.S. Senate and House.

After switching affiliations today, sources say, Barry will wait several days before obtaining the forms he will need to collect the 3,000 voter signatures he must have to be placed on the Nov. 6 general election ballot. Those forms are due to the city Board of Elections and Ethics by Aug. 29.

Key Barry supporters said the mayor hopes to maintain a low profile as he prepares for a council campaign to avoid antagonizing federal authorities or Judge Thomas Penfield Jackson, who has set a Sept. 17 hearing to determine whether the U.S. government intends to prosecute Barry further.

On Friday, a federal jury convicted Barry on one charge of cocaine possession, acquitted him on a second and announced it was unable to reach a decision on the remaining 12 charges against the mayor.

The mayor could receive up to a year in prison, although it is rare for a first-time offender to be sentenced to jail for cocaine possession.

As Barry contemplated his political future, several of his would-be successors campaigned across the city yesterday for votes in the Democratic Party's mayoral primary, which is just over four weeks away.

Ray and Del. Walter E. Fauntroy (D-D.C.) competed for votes in the church-going community. Ray won the endorsement of the Rev. Warren J. Crudup, jurisdictional bishop of the more than 100 Churches of God in Christ in the greater Washington area.

Crudup, speaking at a church convocation in Prince George's County, described Ray as "a man of integrity and leadership, the best hope for healing our racially polarized city."

Crudup's church includes thousands of District residents, as does the United House of Prayer, whose bishop, Walter McCollough, endorsed Fauntroy yesterday. McCollough's endorsement, which is highly prized in city election years, was delivered by his son, the Rev. C.L. McCollough, at the church's main sanctuary on M Street NW.

In an address to 200 worshipers, Fauntroy issued thinly veiled criticisms of Ray for raising large sums of money from the region's commercial interests, and of Barry for his private misconduct as mayor.

"I thank God that during this election, money doesn't vote, people vote," Fauntroy said.

He added that while "our mayor has been delivered from having to go to prison" and all people may seek redemption, "let us not send forth the message to our city and our children that drugs are all right."

"Let's send a message to our young women, 'Don't trade sex for contracts,' " Fauntroy said.

Meanwhile, candidate Charlene Drew Jarvis, who represents Ward 4 on the council, was endorsed by several women leaders in the black community.

Barry spent much of yesterday as he has most recent Sundays, attending church, first at Metropolitan Baptist Church in Northwest, then at Tenth Street Baptist, whose young pastor, A.C. Durant, has become close to Barry in recent years.

"One thing I do know is that God is able," Barry said. "And I also know that the prosecutor may have had a lot of so-called evidence in the case, but God is a better lawyer."

Barry received an enthusiastic reception when he asked the parishioners to pray with him for some of the former friends and associates who testified against him.

"It's painful to sit in the courtroom and see people who are associates of yours over the years," Barry said. "They'll say anything, mostly untrue, just to save themselves."

Barry said the parishioners should pray "that I find, in my heart, forgiveness. It's not easy, but I'm going to try to work on that."