Sen. Charles McC. Mathias of Maryland jumped at the chance yesterday to add his liberal views to the leadership of the Republican-controlled Senate by accepting the chairmanship of the Rules and Administration Committee in the 97th Congress.

Never mind that Mathias' assignment covers such mundane matters as who gets what parking spaces on Capitol Hill, or who will operate the Senate restaurants or stores. The position carries with it the opportunity to influence decisions in a Senate that will include many conservative newcomers. i

In a meeting yesterday of Senate Republicans, Mathias also accepted a position on the prestigious Foreign Relations Committee, even though he had to give up the chairmanship of an important Appropriations subcommittee to do it.

The three-term legislator, long considered one of the staunchest supporters of the District of Columbia in the Senate, also will replace Sen. Thomas Eagleton (D-Mo.) as chairman of the Government Operations subcommittee on governmental efficiency and the District of Columbia, one of two Senate subcommittees that oversees affairs of the city. Republicans still have not decided who will replace Sen. Patrick Leahy (D-Vt.) as chairman of the Appropriations subcommittee that has line-item control over the city's budget. a

Although the Senate Rules Committee does not carry the weight of its counterpart committee in the House, which determines when legislation reaches the floor, its legislative duties include election law and lobbying reform.

The Rules Committee, which was headed by Sen. Claiborne Pell (D-R.I.) in the 96th Congress, also has jurisdiction over the Capitol, Library of Congress and the Smithsonian Institution.

Mathias said he chose a lower ranking slot on Foreign Relations instead of the No. 3 spot on Appropriations because "the development of a consistent and coherent U.S. foreign policy remains the most vital issue confronting the nation today."