David Carter hung tough yesterday, clinging to his seat on the Commodity Futures Trading Commission in the face of a public demand for his resignation from his old Minnesota friend, Vice President Walter Mondale.

Echoing President Carter, Mondale said Gartner should quit because of "ethical apperances" involved in the gift of $72,000 worth of stock to Gartner's children by Dwayne Andreas, chairman of Archer-Daniels-Midland Corp., a major grain dealer regulated by the commission.

In an interview yesterday, Gartner denied any conflict of interest and accused his accusers of acting without having all the facts.

"When you get to talking about implications and accusations and apperances you are really not being fair to a man," Gartner complained.

He vowed he will "at least establish there is no conflict of interest of apperance of conflict" during a scheduled apperance today before the Senate Agriculture Committee.

"There's are an awful lot of people in this city who deal with issues and have friends who are involved with those issues," he added.

Gartner yesterday won an endorsement from CFTC Chairman William Bagley, who wrote to the Agriculture committee on behalf of his fellow commission member.

Bagley did not make the letter public, but in an interview said Gartner's ties to Andreas and Archer-Daniels-Midland would not prevent him from "dealing with better than 90 percent of the business that comes before the commission."

But Gartner lost the public backing of Vice President Mondale, who worked with him for many years when both were protegees of the late Hubert Humphrey.

Mondale's public call for Gartner's resignation was no surprise, because it was Mondale's staff that had privately asked Gartner to quit last week. When Gartner refused, the White House went public, in the process raising questions about how the appointment was handled in the first place.

Mondale's first public comments on the matter were made in a previously-scheduled interview with Associated Press and United Press International.

The vice president - who reportedly had a key role in naming Gartner to the $50,000-a-year CFTC post - said he was "greatly troubled" when he learned of the gift of ADM stock to Gartner's children.

Gartner himself made the gifts public, and in yesterday's interview said he had told Humphrey about the gifts, which were made when Gartner was on Humphrey's staff.

Saying "this has been a very unhappy situation to me," Mondale added, "I think he's an honest man. I think he made a mistake."

He said Gartner should resign "on the grounds that the ethical apperances surrounding that matter were such that he could not operate without public questioning of his integrity and the independence of his judgment.

Mondale said neither he nor President Carter knew of the stock gifts at the time Gartner's appointment was being considered. White House staff members, however, have acknowledged Gartner told them of the stock. They approved the appointment anyway, sending it to the Senate, where Gartner was confirmed in one day.

The Agriculture Committee, which now says it wants to question Gartner further, raised few questions about the stock at the original confirmation hearing.

Gartner refused to comment yesterday on the only new question raised since the hearing - whether some of the stock was transferred to him after the effective date of Senate ethics rules which banned such gifts. An aide described the date question as "a technicality."

One of the nation's biggest buyers and processors of corn, wheat and soybeans, Archer-Daniels-Midland frequently deals in grain futures.

CFTC sources said privately that Gartner's links with ADM chairman Andreas were no different than the ties of other commissioners to the industry they regulate.

Commissioner Read P Dunn worked for the National Cotton Council for more than 20 years before being named to the commission. Commissioner Robert L. Martin was a vice president of Cook Industries, another big grain company.