President Carter has nominated David Gartner, former administrative aide to the late Sen. Hubert Humphrey (D-Minn.), as a member of the Commodity Futures Trading Commission.

The nomination had been expected until the Office of Management and Budget urged the president late last month to abolish the controversial CFTC and replace it with a regulatory organization headed by a single administrator.

OMB's recommendation was sent to key members of the House and Senate agriculture committees the night before the Senate panel began its markup of the CFTC reauthorization bill. Committee Chairman Herman Talmadge (D-Ga.) tabled the administration recommendation without discussion, apparently because of its tardiness, aides said.

A similar lack of success with the House panel now marking up a CFTC bill apparently led to the president's tacit support of the commission in its present form signaled by the Gartner nomination.

Gartner will replace Vice Chairman John Rainbolt II, who plans to begin a private law practice. Senate hearings on Gartner's confirmation are expected to be held May 17, with a swearing-in ceremony May 22.

The Senate and House committees so far have approved reauthorization of the commission for six and three years respectively. Congressional sources said senators are pushing for a five-year compromise on the new term, while some representatives want three years.

The Senate unit also approved an exemption from the CFTC's ban on commodity options firms such as Mocatta Metals Corp. of New York. The House panel, however, wants to leave decisions on the options ban to the commission entirely.

These and other differences in the reauthorization legislation will be worked out in a joint conference session.