When D.C. Mayor Anthony A. Williams ran for office for the first time in 1998, the Washington Teachers' Union broke ranks with other labor organizations and endorsed him.

It was a big boost for the city's former chief financial officer, who had been shunned by most union activists because he had fired more than 200 city workers. Williams was hard-pressed to break D.C. Council member Kevin P. Chavous's grip on labor support.

But with the nod from the teachers' union, Williams (D) suddenly had some political ammunition against Chavous (D-Ward 7), the council's education committee chairman who was initially considered the front-runner in the race. After all, it was the same teachers' union that had catapulted Marion Barry to the city's Board of Education in 1971 and then to the mayor's office in 1979.

"It gave the mayor momentum at the time because I was the education chair. . . . It cut into what should have been my base," Chavous said. "I think the mayor always felt he owed them politically."

Williams's political relationship with top leaders of the union has cooled a bit in recent weeks. Federal authorities raided the homes and offices of former President Barbara A. Bullock and two assistants last week, looking for more than $2 million worth of luxury items allegedly purchased with diverted union funds. No charges have been filed.

One of the assistants, Gwendolyn M. Hemphill, was co-chairman of Williams's reelection campaign this year. She left the campaign a few weeks shy of the general election, shortly after the union's parent body, the American Federation of Teachers, discovered financial irregularities and alerted the U.S. attorney.

Williams had also appointed Hemphill's husband, Lawrence, to run the D.C. Office of the Public Advocate, which handles constituent services. Williams said last week that he and Lawrence Hemphill discussed moving him to a new job until the situation was resolved.

As for the allegations against Bullock, Hemphill and the union's former treasurer, James O. Baxter II, the mayor said, "Due process has to take its course."

"To the extent that there's smoke here and there's substance to these allegations, it's very disturbing and distressing. I'm very, very disappointed," he said.

The profile of the Washington Teachers' Union had risen in recent years because of its association with Williams, whose popularity with city voters was strong enough to overcome a campaign debacle that forced him off the Democratic primary ballot last summer.

Williams ran as a write-in candidate after the D.C. Board of Elections and Ethics disqualified his nominating petitions, which were rife with forgeries and other violations of D.C. election law. In testimony before the elections board in July, Hemphill said she had no knowledge of how the irregularities occurred. The U.S. attorney's office is investigating the campaign activities.

It is unclear what effect the current scandal will have on the influence of the 5,000-member union in future elections.

D.C. Council member Jack Evans (D-Ward 2) said that the teachers' union will probably not suffer a setback for long.

"Any time the leader of an organization is investigated for wrongdoing, it naturally harms the organization," he said. "But the teachers' union has been around a long time. I'm sure they will have someone new and move forward."

William H. Simons, who headed the teachers' union for 25 years until 1991, said he was impressed that under Bullock's leadership the membership received an 18 percent pay increase over three years -- the largest since 1968.

"They were influential in the reelection of Anthony Williams," Simons said. "You don't get a contract like that unless you have a good working relationship with the mayor."

Asked about the raises, Williams said, "There's no direct quid pro quo."

When Williams ran in 1998, Hemphill lived in voter-rich Ward 4, which Williams desperately wanted to win, and she was an official in a union up for grabs.

Norman C. Neverson, chairman of the D.C. Democratic State Committee, said he had been retired from political activism when he decided to work with Hemphill, a neighbor and friend for 35 years, in 1998 to get Williams elected.

"You want to be able to have on your team agents who can make tremendous differences in terms of the electorate," Neverson said.

Neverson said that teachers are reliable campaign workers who pass out political literature, work at balloting locations and advocate on various issues beyond schools and education. However, some political observers say that the teachers' union has grown weaker in recent years because nearly half of its membership lives in Maryland and Virginia.

Regardless, D.C. Council Chairman Linda W. Cropp, a former teacher who credits the union with helping her win her first term on the school board in 1980 and every council election, said most candidates covet the teachers' endorsement.

Chavous said that by backing Williams, the union made a strategic move, forging a strong relationship between a political novice and a struggling labor organization. It paid off for both, he said.

"Frankly, their clout was enhanced when Tony Williams became mayor," Chavous said. "He really wasn't that steeped in hands-on knowledge of the school system, and he depended on them. The mayor made sure to include them at the table."

Staff writer Craig Timberg contributed to this report.

Ex-teachers' union officials Barbara A. Bullock, left, and Gwendolyn M. Hemphill are accused of using union funds illegally.