D.C. City Council Chairman David A. Clarke might easily be worried about losing a major battle over rent control, especially since the issue is considered crucial to many of his constituents and comes at a time when any signal of political vulnerability could influence the 1986 elections.

He's not, though.

"Whoever runs against me will run against me," Clarke said recently. ". . . I don't feel politically unsafe at all. My political indicators are such that I'm not worrying."

Clarke -- who struggled for months to get the single vote he lacked to pass his rent legislation -- was handed an embarrassing defeat by his colleagues. But some labor leaders, senior citizens and tenants say they do not question his strength as chairman and would support him if he ran for reelection in 1986.

On the other hand, some tenants have vowed they will oust council members who opposed the Clarke bill. Besides Clarke, six council members are up for reelection next year. A seven-member majority was responsible for the council's initial approval of legislation that substantially altered the Clarke rent bill. The council will take a final vote on Tuesday.

The legislation would authorize larger rent increases and lift controls from some properties, including single-family homes as they become vacant and, in four years, all apartments as they become vacant if the city has a 6 percent vacancy rate and if a rent subsidy program is funded and operating.

Clarke clearly has held on to his political base, despite those changes to the rent bill, but it is uncertain whether those supporters will be sufficient to reelect him to the chairmanship.

In District politics, the offices of mayor and council chairman are the most attractive for ambitious politicians. Political observers note that three council members viewed as potential candidates for chairman voted against the Clarke bill: Betty Ann Kane (D-At Large), John Ray (D-At Large) and Charlene Drew Jarvis (D-Ward 4). They presumably would have the support of the real estate industry, one of the city's strongest political lobbying groups, in bids for the chairmanship.

The fourth member viewed as a potential Clarke challenger is John Wilson (D-Ward 2), who supported Clarke's rent bill.

Among people who have worked with him, observed him and lobbied him, assessments of Clarke's strengths and weaknesses as chairman are often contradictory.

To one council member, Clarke has power that has gone "unused and untapped." To another, the chairman is "heavy-handed" and, behind the scenes, "a dictator." To yet another, he strives to avoid the appearance of "using his position to undermine others."

Clarke's supporters and critics alike agree, however, that the chairman is unlike many politicians, in that he is comfortable maintaining a low profile.

"He's able to lead the way without constantly being in the limelight himself," said Ted Gay, a member of the Democratic State Committee. "He's perfectly happy when his fellow council members are doing a great job because that reflects on him."

Clarke, the District's second-highest elected official, is very much a man of his times as a civil-rights-leader-turned-politician, with deep roots in his native city, including a public school education, college at George Washington University and Howard University Law School. First elected to the council in 1974, he represented, for two terms, the heavily liberal Ward 1.

Clarke agrees with Gay's assessment and acknowledges that his current stance is different from the advocacy role he assumed on the council before he became chairman in 1983.

Clarke said his duty as chairman is to take a position on issues and try to bring about a compromise when necessary. Unlike the mayor, who has patronage to use, Clarke says his only tools are communication and negotiation.

"There is not the ability here to swap votes," said Clarke. "There are no consistent voting blocs here. That is a strength of the City Council. The chairman cannot run the City Council by developing a consistent faction. There should not be a faction."

At times, Clarke appears to shun the publicity that some elected officials thrive on. When speaking of the council's accomplishments under his leadership, he carefully avoids using "I." Asked about issues before the council -- such as the development of a council agenda or whether the council would seek to provide tax relief in the fiscal 1986 budget -- Clarke responded with "no comment" or "I can't get ahead of my members."

Wilson, who characterizes Clarke as an effective manager, said he "tries desperately to keep people working together." As a politician, Clarke draws little attention to himself because he frequently agrees with Mayor Marion Barry, Wilson said.

"If he is not in conflict with the mayor, he's not going to get a lot of attention. You could die in obscurity in this body if you agree with 90 percent of what the mayor wants to do."

Clarke also has a habit of commenting on issues long after other politicians have moved on to other matters. "Some people have told me I should be ahead of the events, rather than behind them," Clarke said. "But I don't rush to the hopper. Often, my responses to issues are after a call from the press."

Clarke maintains that the council has gained greater independence under his leadership. He noted the council's shifting of millions of dollars in the last three budgets and reduction of $12 million from the mayor's proposed fiscal 1985 tax package.

Since he became chairman, and in citing other council accomplishments under his leadership, Clarke noted that the council adopted a comprehensive plan to guide such things as land use and economic development, awarded a cable franchise and succeeded in overriding two mayoral vetoes.

Kane said Clarke has not usually tried "to win for his side," but "allowed coalitions to form on many issues." Kane said such an approach has been effective because it forces the chairman to consult with the members and the members with one another.

Yet, some council members argue that Clarke's low-key approach is rarely as altruistic as it appears.

"The chairman has to catch up with the council if he intends to lead the council," said Charlene Drew Jarvis (D-Ward 4). "The members take on hard issues and he becomes the beneficiary without, in fact, going on the line."

Clarke remained quiet while Jarvis pushed for greater council authority in the city's Housing Finance Agency and while she led demands that the council take a more visible role in running the government.

Despite his high profile on the rent control issue, some council members now maintain that Clarke knew a majority of the council members wanted changes in the current rent law but introduced a bill that was identical to the current law for political reasons.

"Dave Clarke is one of the most manipulative politicians I've ever met," said Ray, who led the opposition to the Clarke rent bill. "He has this view that no matter what he thinks, white voters are going to vote for him and that he has to appeal to the downtrodden. He saw rent control as one way to get out there to scream and yell about what he's doing for the poor to send that signal. His position on rent control is 90 percent political and 10 percent substance."

Clarke called Ray's comment "terribly personal."

"The chairman's style has to be nonconfrontational to be effective," said Clarke. "I don't run away from confrontations or a debate, but I don't choose to call people names such as Mr. Ray just called me."

Clarke said he made every effort to win passage of his rent bill.

"I told the voters I would stand up for what is right and I would try to compromise," Clarke said of the rent issue. "I will not win every issue and I will not lose every issue. But that is not a test of leadership." Representatives for pro-rent control groups -- labor and tenant leaders and senior citizens -- who backed Clarke when he ran for council chairman in 1982 say that Clarke does not have to prove himself to them.

"I think that he has been true to the coalition that supported him and helped elect him," said Joslyn Williams, president of the Metropolitan Washington Council, AFL-CIO. "As a politician, you make sure your constituents see you as a person who will fight for them and not sell them out. If Clarke did not win on rent control , it was not for a lack of trying."

Valerie Costelloe, a member of the Ward 3 Advisory Neighborhood Commission and a tenant activist, said that she would "walk every street and alley in this city" for Clarke in 1986, no matter what office he might seek.

"He has put everything on the line for us," Costelloe said. "Clarke has come out for the poor and middle class and elderly. John Ray and the rest of them want to turn this city into a city for the rich and they don't care what happens to the poor."

Costelloe said that if the council does not change its vote on Tuesday, Kane, William R. Spaulding (D-Ward 5) and Nadine P. Winter (D-Ward 6), three members who voted against the Clarke bill, will be targeted for defeat if they seek reelection in 1986.