Richard E. Obenshain, a leader in the resurgence of the Republican party in Virginia during the last 10 years, today announced his candidacy for the U.S. Senate.

Obenshain is viewed as a conservative pillar in a conservative party, but after his announcement speech to 400 supporters he told reporters that he considers himself to be a considers himself to be a "Jeffersonian democrat with a small d."

"My strongest commitment is to individual liberty, to the Jeffersonian ideal of limiting government's interference with the rights of citizens," he said.

He said in his announcement speech that if elected he will make tax reductions and control of the "power of impersonal bureaucracy" the primary goals of his Senater term.

Obershain seeks to succeed Republican Sen. William L. Scott. who has announced his intention to retire. In seeking the nomination,which will be decided at a party convention in June, he begins with impressive backing from Republican regulars.

The letter inviting Republicans to his announcement ceremony carried the names of 200 party supporters, including 55 city and county Gop chair persons.

His leading opponents in the contest for the republican nomination are former Gov. Linwood Holton and former Secretary of the Navy John Warner. State Sen. Nathan H. Miller of Rockingham County also has announced as a candidate.(See OBENSHaLN, B5, Col 1)(OBENSHAIN, From B1)Obenshain is a former chairman of the state Republican Party and co-chairman of the National Republican Party. He was narrowly defeated in 1954 when he sought the U.S. House seat for Virginia's Third District, which includes Richmond and its suburbs. In 1969, he lost the state attorney general election to Andrew P. Miller, but in doing so became only the second Republican to get more than 400,000 votes in a Virgina election.

Miller is one of at least eight Democrats considered likely to run for the Senate next year. two Democrats, state Del. Carrington Williams and former Fairfax County Board of Supervisors Chariman Frederick A. Babson have already announced their intentions to run. ALso mentioned as possible Democratic candidates are state Sen. Hunter B. Andrews of Hampton, former Fairfax Supervisor Rufus Phillips, state Sen. Clive L. DuVal II of Fairfax. Rep. Herbert E. Harris and state Sen. James T. Edmunds of Lunenburg County.

Until the later 1960s Republican nominations for statewide office were prizes of little value. Since 1966, however. Democrats have won only four of 16 statewide contest - including presidential contests - and have slipped to a minority of four in the state's 12-member congressional delegation.