The telephone call from Rosalynn Carter to LaBelle Lance Aug. 10 signalled a dramatic White House change of climate in the Lance affair, carrying implications for the duration of the Carter administration going far beyond Bert Lance.

From that moment, President Carter's support of Budget Director Lance miraculously expanded. White House aides who had been predicting Lance's doom suddenly began forecasting his resurrection days before the President's public endorsement on Aug. 18. Explaining the switch, they privately told each other the press crusade against Lance could happen to any of them - perhaps including Carter.

Although Lance may yet fall, the fact remains the President did not abandon his friend as was widely expected. Carter thereby changed his presidency, sacrificing its sanctimonious aura for a more mundane creed of loyalty to subordinates that will be better appreciated by politicians than by Common Cause. Although his precise motivation remains unclear, there is no doubt President supported his fellow Georgian at great risk of anger from the liberal establishment. Similar anger was also clearly evident at the President's press conference yesterday, with Carter himself target.

The decision to take that risk is symbolized by the First Lady's call to Mrs. Lance. "I would say that was an extremely significant development," a presidential aide told us. That is certainly an understatement. Mrs. Carter is often her husband's most influential adviser her call marked the end of chilling presidential isolation for Lance.

The standard White House explanation for the changed climate is advance knowledge that the report by Comptroller of the Currency John G. Heimann would charge no criminal violations. Yet Rosalynn's telephone call came days before Heimann's findings could have been known and when it was still presumed his report would be sent to the Justice Department for possible prosecution.

"I think that a lot of us just began to think. "There but for the grace of God go [WORD ILLEGIBLE] confided one member of the Carter inner circle. "If the press could do this to Bert, they could do it to anyone here." Senior aide Hamilton Jordan, suspected by some of Lance's friends though definitely not by Lance himself) of shedding few tears over the fall of a rival power source, increased his support of Lance. It was Jordan who first encouraged Mrs. Carter's symbolic telephone call.

Partially responsible for the change was the ghost of Ted Sorensen, hastily abandoned in January by Carter as his CIA director. According to White House insiders it was decided the President ultimately could not survive if he failed to defend senior officials under attack.

But a more sinister formulation of that principle, suggested on the fringes of the administration is that the Carter high command also worried that the President's intimacy with Lance, particularly with political financing, almost made him an accessory before the fact. Carter's use of Lance's bank plane, apparently without reimbursement, is cited by friends of Lance as merely one of innumerable financial links between the two men.

Whether impelled by loyalty, self-preservation or a combination, the new mood at the White House expressed itself in suddenly supportive private statements for Lance beginning about Aug. 12. When the Heimann report was released Aug. 18, Jordan and Press Secretary Jody Powell urged the President to fly here from Camp david to embrace Lance on national television.

The President's aides were shaken by the press reaction. When reporters went on the attack at the Aug. 18 press conference, the White House was genuinely upset. Key aides were disappointed when the Los Angeles Times called for Lance's resignation and James Reston wrote a critical column.

What worries the White House even more are the Republicans. There are ominous overtones to the warning by Illinois Sen. Charles H. Percy, senior Republican on the Governmental Affairs Committee, that Lance cannot perform his duties if the investigation stretches on for weeks. Consequently, Lance is being urged to shed his original problem by selling his bank stock with the utmost haste.

However difficult the future proves, Lance now strides toward it arm-in-arm with the President. That is interpreted here as a setback for Treasury Secretary Michael Blumenthal (on vacation while Lance was resurrected) as well as many administration officials who like neither Lance's style nor fiscal conservatism.

"Personally, I could never see why the President would name a man like Lance to that job in the first place," a middle-level official told us when Lance seemed finished. So, even if partially caused by self-preservation. Jimmy Carter's decision to stand by "a man like Lance" - a conservative Southern banker widely distrusted by this administration's dominant ideological strain - involves much more than the fate of Bert Lance.