Without significant opposition either on Capitol Hill or from city leaders, the U.S. Senate is moving to eliminate the Senate District Committee and transfer its functions to a new subcommittee.

The Senate Rules Committee, which is required by midnight Tuesday to report out a bill to reduce the number of Senate committees, has agreed to place District affairs under a revised Senate Government Affairs Committee.

The plan would permit Sen. Thomas F. Eagleton (D-Mo.), chairman of the Senate District Committee, and Sen. Charles McC. Mathias Jr. (R-Md.), its ranking minority member, to transfer to the Government Affairs Committee, where they will serve on the new subcommittee, that will review legislation affecting the city.

Eagleton and Mathias had written a letter to the Senate Rules Committee favoring retention of the full Senate District Committee as a more efficient was for the Senate to oversee the federal city.

Despite the prospective loss of their full committee, neither senator testified or actively worked to maintain the Senate District Committee in the face of the committee consolidation plan drawn up by a special panel headed by Sen. Adlai E. Stevenson (D-Ill.).

Instead of last session's seven-senator District Committee there is likely to be only a five-member subcommittee reporting to a Government Affairs Committee that would be expanded to 20 senators from the previous 14-member Government Operations Committee.

Also moving with Eagleton and Mathias to the revised Government Affairs Committee would be Sen. Quentin N. Burdick (D-N. Dak.), chairman of the Senate Post Office and Civil Service Committee, which similarly would be reduced to subcommittee stature.

Under the proposal, the Senate District subcommittee would report to a full committee whose membership could reverse the subcommittee.

Under a new arrangement, review of bills enacted by the City Council could take longer, since it would be done by the subcommittee and then by the full committee.