Arlington Circuit Court Judge Charles S. Russell was chosen today by Democratic legislators as the state's newest Supreme Court justice, ending a hard-fought political battle over the successor to retiring Justice Albertis S. Harrison.

Russell won the balloting in both the Senate and the House Democratic caucuses by only one vote, but following Virginia tradition Democrats will support his election unanimously when the nomination comes to the floor. Russell, a judge since 1967, will be the first Northern Virginian appointed to the seven-member high court in 20 years.

The battle over the Supreme Court judgeship this year pitted Russell, 55, against former legislator William H. Hodges, now a Circuit Court judge in Chesapeake.

The Northern Virginians' narrow victory was owed in large part to an alliance with legislators from the Southwest who last year looked north for support of Justice Roscoe B. Stephenson Jr., then a nominee to the high court. Hodges' support came from his native Tidewater and among the older legislators who served with him more than 10 years ago.

"It was very, very close," said Sen. Clive DuVal (D-Fairfax), chairman of the 31-member Senate Democratic caucus, where the outcome was kept secret.

"It was super," said Del. James Almand (D-Arlington), who nominated Russell in the House Democratic caucus. "The vote was just what we counted on."

The House caucus, which met openly, split 33 to 32 with crucial votes coming from supporters of Richmond Circuit Court Judge Marvin Cole. According to one legislator, the Northern Virginians are pledged to support Cole the next time a vacancy on the high court occurs.

Russell, a candidate for Supreme Court vacancies for three years in a row, was the only candidate this year to win the endorsement of the top three lawyers' groups in Virginia.

"It is important not just to lawyers in Northern Virginia but also to litigants who want a voice on the court familiar with Northern Virginia and its problems," said Sen. Edward M. Holland (D-Arlington), who ran Russell's campaign in the Senate.