Last Dec. 3, Matt Coffey, an official of the Carter-Mondale transition group in Washington, received a telephone call from an FBI agent who said he had been asked to pass on a warning.

There might be some problems in the banking background of T. Bertham Lance. President-elect Carter's choice to head the Office of Management and Budget, the agent said.

The call came in at about 1 p.m. in less than two hours, down in Plains, Ga., Jimmy Carter was to hold a press conference to introduce his choice of budget director to the world. "It was too late to do anything even if we wanted to," Coffey recalled later.

That call was one of the first early warning signs of what would become known this summer as the Lance Affair, which now so clearly threatens to end the short, happy government career of one of the President's best friends.

But a day or two later - in what is something of a pattern in the whole Lance matter - the warning was withdrawn. The agent called back and told Coffey that a Justice Department investigation of overdrafts in a Lance campaign account - the subject of the first call - had been closed within the last few days.

The calls to Coffey, who passed the information on to his boss, Jack H. Watson Jr., now the White House Cabinet secretary, go to the heart of a central issue in the Lance Affair - how much did the President-elect and his inner circle of advisers know about Bert Lance's background when they proposed him as the nation's budget director?

Did they know enough to reconsider the nomination, and should they have passed more of what they knew on to the Senate Governmental Affairs Committee?

The answers are not clear. In one sense, the Carter aides knew to litte, for the information that came to them was sometimes fragmentary and contradictory.

They had access to an FBI report with embarrassing, even damaging information about Lance's practices as a banker.

But in the same report, some of the people who knew the most about Bert Lance the banker told the FBI that those practices, sloppy and questionable as they may have been, did not make Lance unfit to run OMB.

In another sense, the Carter aides knew too much. If they had been dealing with someone else, they might have paused and asked more questions. But this was good old Bert, a member of the inner circle of Georgians.

They knew he tended to be sloppy, like so many of them. Information that might have touched a nerve among the more politically sensitive Carter aides appears to have been discounted in the case of Lance.

How much the President knew at the time is not clear. According to White House aides, Carter was never shown the Jan. 6, 1977, FBI background report, which until this summer's investigations contained the most complete account of Lance's banking activities.

The then-President-elect and Lance discussed some of the problems Lance encountered when he headed the Calhoun, Ga., First National Bank last Nov. 15 at Carter's home in Plains. But how much detail they went into has remained a mystery.

The FBI report was read by key Carter aides and has since been made available to The Washington Post. If contained an extensive description of the overdrafts on the Lance-for-governor campaign account, the fact that possible criminal violations were involved and that the case had been referred to the Justice Department.

In another section, taken from the files of the U.S. attorney's office in Atlanta, there was a listing of overdrafts on personal accounts. It showed that in 1973 and 1974 Carter's choice as budget director had allowed himself, his wife, one of their companies and at least a half dozen relatives and in-laws to overdraw their accounts by a total of more than $500,000.

The Carter aides knew this at the time Lance breezed through his Senate confirmation hearing.They failed to act on the information, and they still defend that decision today.

"I know politically embarrassing information about virtually every member of the Cabinet," one White House official said recently. "The decision we had to make was whether it made him unfit for the office."

Emphatically, White House officials still insist, it did not. For the same FBI report - like the second call to Matt Coffey - contained information that tended to discount and mitigate against the most questionable Lance practices.

The Justice Department by then had closed its investigation of the campaign overdrafts. The comptroller of the currency had terminated the enforcement agreement that grew out of some of the same practices, believing the Calhoun bank then to be following standard banking procedures.

Scattered throughout the report, there were endorsements of Lance, not only from his friends in the banking business, but from some of the people who had investigated him and his Calhoun bank.

The overdrafts on the personal accounts, one official said, "involved no willfulness, no violation of criminal law." An official of the comptroller's office in Atlanta said overdrafts by bank officials were "not at all uncommon," practicularly in rural Georgia banks.

An official of the comptroller's office in Washington who was familiar with the Calhoun bank case told the FBI he considered Lance to be "very capable and well-qualified" and that he knew "nothing unfavorable about Mr. Lance."

Robert Lipshutz, now counsel to the President, was one of those who saw the FBI report. He said in a recent interview that he shows FBI files to the President only when he and his staff come across something they feel they can't handle, in the case of Lance, he did not.

"Anyone who saw the FBI report would come to the same conclusion." White House press secretary Jody Powell said in defense of Lipshutz. "There had been problems in the past, they had been dealt with by the appropriate agencies and it was a closed matter. Bob Lipshutz had to decide if the information in the report warranted further action. It was his conclusion there was noting there to indicate a continuing problem."

Lipshutz not only did not show the file to the President, he did not give it to the Senate committee. Buit it is not the practice of the Carter administration or other administrations, to volunteer FBI background reports.

Lipshutz said he had had three or four requests from Senate committees to see FBI reports, and he always complied by showing them to the chairman and ranking Republican. But the Governmental Affairs Committee, in the case of Bert Lance, never asked.

So the Lance FBI file, containing much of the information that would bring Lance this summer to the brink of a forced resignation, remained buried in the White House through the first eight months of Carter's term.

In the meantime, Lance's power grew and his outgoing, affable personality made him among the most popular figures in the new administration.

It is impossible to tell how much the judgments of Carter's aides were colored by their intimate knowledge of Lance and fondness for him. But even this summer, when there were new revelations, they tended to discount them.

When it was learned that Lance violated a loan agreement by pledging the same block of stock as collateral for another loan, one of them just shook his head and said, "If I know Bert Lance, he just signed that loan agreement and never even read it."

Testifying before the Governmental Affairs Committee last week, former acting Comptroller of the Currency Robert Bloom tried to explain why, knowing what he did, he had endorsed Lance both to the committee and in a statement to an FBI agent making the background check.

"Nobody wants to be the skunk at a garden party," he said.

Bert Lance's friends in the Carter White House shared that sentiment.