The FBI yesterday began contacting former officials of the 1980 Reagan and Carter presidential campaigns in its investigation to determine how Reagan's organization obtained documents from the Carter White House, and a Reagan spokesman said the president would respond to any inquiries.

"The president will be totally responsive to any question put to him," White House spokesman Larry Speakes said in Santa Barbara, Calif., where President Reagan is spending the holiday weekend at his ranch. "That is at the moment hypothetical. The FBI has not asked. I'm sure he will respond in some fashion to any inquiry."

FBI sources said agents from the Washington Field Office plan to begin interviews early next week with everyone who might know about the matter, ranging in the Reagan administration from former campaign secretaries to such high-ranking officials as CIA Director William J. Casey and Office of Management and Budget Director David A. Stockman, according to bureau sources. The FBI also has set up interviews with two former aides to President Carter, David M. Rubenstein and pollster Patrick Caddell.

FBI officials mapped out the investigation to see if criminal laws were violated in a meeting Thursday at the Justice Department. Officials said they are determined to avoid potential criticism that they failed to interview key witnesses.

"This is obviously a high-profile inquiry," one FBI official said. "If someone with knowledge of this operation says later that 'the FBI never talked to me,' it could create problems."

The initial interviews will not be conducted under oath, but sworn testimony could be taken later if there are discrepancies in various accounts, officials said.

On Capitol Hill, Rep. Don Edwards (D-Calif.) said he had little confidence in the investigation, and urged Attorney General William French Smith to appoint a special, independent counsel to run the probe. Edwards told reporters that "there is a clear political conflict of interest" in having Smith supervise it because Smith "is a political appointee and close personal friend" of Reagan. Edwards, chairman of the House Judiciary subcommittee on civil and constitutional rights, said that if the full committee formally requests an outside counsel and Smith refuses, "it would look like a cover-up."

"It seems to me what's political here is the partisan politicking that's surrounding this," responded Justice Department spokesman Thomas P. DeCair. "If the current investigation warrants the attorney general asking a court to appoint an independent counsel, he'll do it. The Justice Department is perfectly capable of investigating any part of the government."

A House Civil Service subcommittee, chaired by Rep. Donald J. Albosta (D-Mich.), also is investigating how Reagan campaign aides obtained hundreds of pages of Carter briefing documents for Reagan's October, 1980, debate with Carter.

Justice Department officials have maintained that they are not required to name an independent counsel because no allegations have been made against a specific, high-ranking government official covered by the 1978 Ethics in Government Act. At the department's urging, Congress changed the ethics law last year to give the attorney general discretion to dismiss allegations of little merit.

Meanwhile, White House spokesman Speakes said Reagan was not aware that an "intelligence operation" had been set up during his campaign, Washington Post staff writer Juan Williams reported from Santa Barbara.

Speakes was responding to a Post report that Casey, while serving as Reagan's campaign manager, set up what he called an "intelligence operation" to monitor whether Carter would stage an "October surprise," such as a move to free the U.S. hostages in Iran, near the end of the 1980 campaign.

White House counsel Fred F. Fielding is continuing to look into the case, talking to administration officials and having Reagan campaign papers at the Hoover Institution at Stanford University reviewed for any related information, according to Speakes.

Reagan has "directed the members of the White House staff to cooperate fully with those seeking the facts," Speakes said. "There is no doubt in anyone's mind where the president stands on the matter."

Reagan also has been following media reports closely, according to Speakes, who said most of the information is new to Reagan. He added that the president has no knowledge about whether the Reagan campaign had a "mole" inside the Carter campaign or White House.

"The Justice Department is looking into the whole matter," Speakes said, "moles and woodchucks and whatever else."