AFL-CIO President Lane Kirkland brushed aside complaints today from Democratic presidential hopefuls John Glenn and Alan Cranston and set the stage for an early labor endorsement of former vice president Walter F. Mondale.

The executive council of the AFL-CIO is to decide Tuesday whether to advance the date of endorsement from December to early October, and Glenn conceded, "I am realistic enough to know . . . it will probably not be in my direction."

Sens. Glenn (D-Ohio), at a news conference here, and Cranston (D-Calif.), in a letter to Executive Council members, complained that the federation was speeding up the procedures to help Mondale. But they vowed to fight for rank-and-file support in the 1984 primaries despite the endorsement decision.

Kirkland said he thought all the candidates had been given a fair chance to prove themselves in appearances before the executive council and individual union conventions. Referring to Glenn, he said, "There is no reason to assume he will not get full and fair consideration."

Acknowledging the likelihood of splits in labor's ranks, Kirkland said, "An endorsement is not a way of instructing people how to vote."

But neither Cranston nor Glenn underestimates the practical value of putting labor's political machinery at the disposal of the Mondale campaign.

The only question before the executive council Tuesday is whether to move up the endorsement decision from the original mid-December date to the time of the AFL-CIO convention, which is the first week in October.

But Cranston and Glenn both treated the procedural question as if it were tantamount to handing the endorsement to Mondale.

"I can't believe that labor would turn its back on me after our long and close association with one another, especially when the issue is only a matter of timing and not one of principle," Cranston wrote members of the Executive Council.

Glenn said he had told Kirkland in a meeting last Friday that advancing the date "would be of benefit to only one candidate Mondale , and obviously I disagree with that."

The senator said he had overcome labor endorsements of Democratic primary rivals in Ohio, adding, "I expect to do very well" with rank-and-file workers, "no matter what they do here."

Cranston aides hinted that he may fight the Mondale endorsement on the floor of the AFL-CIO convention, but the Glenn camp said they regarded any such effort as "futile."

Speculation today was that the council will ask Kirkland to call a meeting of the federation's general board--the 96 affiliated union presidents plus a few other top officials--to submit an endorsement recommendation to the 3,000-member convention, opening Oct. 3 in Florida.

Gerald McEntee, the pro-Mondale president of the American Federation of State, County and Municipal Employes (AFSCME), said this morning that "in our judgment, Mondale is awfully close" to having the 9 million votes required for endorsement.

Each union president casts a vote weighted to the membership of his union, and a two-thirds majority vote is required for endorsement. About 17 large unions could control the decision.

On the eve of the vote, Kirkland sought to play down any idea that the AFL-CIO was trying to play kingmaker or dictate the votes of union members.

"The question of whether the labor vote is monolithic is a straw man," he said. "I don't know anyone who ever thought it was."

Instead, he said, "This endorsement is an act of internal governance. It's the guidance we get from our membership as to what our course of action should be. Without that, we are powerless to do anything within the political arena."

Since Kirkland succeeded the late George Meany as head of the AFL-CIO he has put increased emphasis on retooling labor's outmoded political machinery with the latest computer technology, polling and communications techniques.

After a successful trial run in the 1982 midterm election he is eager to put it to maximum use in selecting the Democratic nominee and then defeating President Reagan.

Glenn campaign aides who sat in on a Sunday briefing on labor's plans for 1984 given by John Perkins, director of the AFL-CIO Committee on Political Education (COPE), said they were awed by the scope and sophistication of the operation. They said it would nearly double the organizational resources of the endorsed candidate.

"We can run head-to-head with Fritz" Mondale, one Glenn aide said. "But with 'Fritz and Fritz,' forget it."

While Glenn appeared to make little headway in slowing the AFL-CIO rush to Mondale, his stopover in Boston did yield some political dividends.

Two members of the Bay State's House delegation, Reps. Brian J. Donnelly and Nicholas Mavroules, gave Glenn their endorsements, joining Sen. Paul Tsongas (D-Mass.) in the Glenn camp. Mondale had earlier obtained the support of Reps. James M. Shannon, Joseph D. Early and Barney Frank.

The executive council, focusing today on the economy and industrial policy, called the recent drop in unemployment "welcome," but Kirkland compared it with the feeling of relief that comes after "being hit over the head with a hammer, when the pain subsides a bit."