J. C. Turner, a stout, plain-spoken labor leader with thin snow-white hair, excused himself as he interrupted a brief interview to answer an urgent, long-distance call from New York City. The 62-year-old Turner listened intently, his eyes blinking rapidly as he stared at his crowded desk calendar.

"Well," said Turner in a gentle but firm voice, "you'll have to send a letter before we make a financial contribution to his campaign. No, no, I just need a letter and then it'll be all right."

Turner is general president of the International Union of Operating Engineers, whose men run the heavy machinery at construction sites. He is called "the gray eminence" or "Mr. Labor" of Washington's trade union movement.

For more than 35 years, he has been a close friend to Mayor Walter E. Washington, who learned, in part, how to maintain good relations with union leadership from Turner.

Born in Beaumont, Tex., Turner moved to the District of Columbia in 1932 at the age of 16. Two years later he became active in Operating Engineers Local 77 politics, and in the intervening 44 years moved up to head that union's international office.

Along the way he became intricately involved in District of Columbia politics, serving for more than two years on the city's first appointed City Council in the late 1960s.He organized politically the city's labor movement while serving as president of the Greater Washington Central Labor Council from 1958 to 1972.

Turner, who comes out of the trade union movement's egalitarian thrust of the 1930s, was in the forefront of desegregation efforts in Washington when it was not popular in the city's rigidly segregated society. Turner was also politically engaged in the fight for home rule.

In the 1940s and 1950s, he and the mayor were both members of the Washington Housing Association, an integrated group interest in providing better housing for the poor. "The only place we could eat then for lunch was the YWCA at 17th and K Streets (NW)," Turner recalled during a recent interview. "That was the only place that would accept an integrated group."

Turner is unswerving in his support of the mayor.Turner says his support does not influence how other labor council union officials line up on endorsing the major but some labor leaders disagree with his assessment of his influence.

Despite being a man who "lived and breathed" District of Columbia politics for three decades, Turner today likes to leave one with the impression that he is completely divorced from the city's local labor and political activities.

Asked by a reporter what was the quid pro quo of labor's strong relationship with the mayor, Turner - without a blink - said, "I don't know. You'll have to ask the local union people."

In 1974, according to sources close to the mayor and Turner, the politically astute Turner was actively involved in Washington's campaign strategy. Every Saturday, according to one source, from February to June, Turner attended weekly strategy meetings held at the home of Charles T. Duncan, a former corporation counsel for the city and one of the mayor's close advisers.

From June until Washington's general election victory in November, Turner attended the weekly Tuesday evening meetings of the mayor's steering committee held at his campaign headquarters, sources said.

"There are still delegates to the Central Labor Council who feel if Jay says something it is tantamount to an order," said Arline Neal, president of Local 82 of the Service Employes International Union and a stalwart Turner follower. "That is why he has stayed away from the (labor) council meetings. He is afraid of his own influence. He is 'Mr. Labor' in this town."

As Turner has taken a less public role in the hurly-burly of District labor relations and politics, a cadre of labor officials whom he groomed during his year as "Mr. Labor" here has moved into leadership position. They include Neal, Henry Brock of the Building Laborers Local 74 and present head of the labor council. Robert E. Petersen, and three officials of the largest city union local in private industry, Donald R. Richardson, Minor Christian and Joseph A. Beavers of Local 25 of the Hotel and Restaurant Employes Union.

Although Richardson, secretary treasurer of Local 25, denies it, labor council leaders point to him as Turner's heir-apparent. Richardson, 38, has a reputation for "playing hardball in any tradoffs" when seeking gains for the 9,000 members of his local, 6,000 of whom live in the city, sources say.

"Ron is very different from J. C. (Turner)," said one high'level labor official who is close to both men. "Jay relies on his personal ability to persuade people while Ron uses his union as a power base. He's more aggressive, more abrasive than J.C. is," the source said.

In matters affecting the labor council unions in the metropolitan area, the source continued, Richardson deers to Thomas McNutt, who heads the Retail Employes Local 400 with 16,000 regional members. "When it comes to District (of Columbia) matters," the source said, "McNutt defers to Richardson. That is the way it is done in the trade union movement. The union local with the largest membership (in a given geographical area) takes the lead."