Former Navy secretary John W. Warner has spent twice as much money in his effort to win the Republican U.S. Senate nomination in Virginia as his two principal opponents, but has done it without the help of one of former Washington associates.

J. William Middendorf II, who served as Warner's undersecretary before succeeding him in the Navy post, instead gave $1,000 - the maximum legal contribution - to former national GOP cochairman Richard D. Obenshain, according to financial statements filed yesterday. Warner received a $500 contribution from Middendorf's wife, Isabel.

A spokesman for Middendorf,a Washington banker, said yesterday that Middendord "thinks both of these candidates are outstanding and that either will made a wonderful senator," but that Middendorg's long association with conservative Republicans influenced him to support Obenshain.

According to the reports, Warner has spent $425,591 in his efforts to win the party's nomination that will be decided at a June 3 convention in Richmond.Obenshain, considered a leader of the conservative wing of the Virginia Republican Party, had spent $138.028 and former governor Linwood Holton, $77,555. State Sen. Nathan H. Miller of Rockingham County reported expenditures of $25,195.

Warner's spending, believed to be a record for a Virginia convention, was largely financed by loans from an Alexandria bank controlled by a holding company that Middendorff heads.Warner's loans, totaling $341,000, came from the National Bank of Northern Virginia and were secured by funds he has on deposit at the bank.

Middendorf is president of Financial General Bankshares Inc., a Wshington bank holding company that controls the Northern Virginia bank.

While the Middendorf's were putting ideology above official ties in apportioning their campaign contributions, they apparently were not moved at all by neighborhood associations. Holton, a party moderate who lives across the street from the Middendorfs in McLean, showed no contributions from either of them.

Both Obenshain and Warner have relied on contributions from individuals and political action committees. The committees are permitted to contribute up to $5,000 to a candidate. Both have raised more money in contributions than Warner, who listed gifts totalling $84,237.

Obenshain reported a contributions total of $140,464 and Holton $86,167. Miller reported contributions of $26,335, including $12,000 of his own donations.

Federal law puts no limit on contributions by a candidate to his own campaign.

Obenshain has done the best of the Republican candidates in attracting contributions from political action committees, many of them dedicated to conservative causes. HIs committee gifts totaled almost $20,000 and included $5,000 from the Citizens for the Republic in Santa Monica, Calif., and $4,000 from the Gun Owners of America.

The four candidates are seeking the nomination to fill the seat being vacated by tht retirement of Republican Sen. William L. Scott. Obenshain is considered the leader in unofficially committed delegate votes but is thought likely to come up short of a majority on the first convention ballot.

The Democrats will choose their nominee on June 10 at a convention in Williamsburg. CAPTION: Picture 1, John W. WARNER . . . has spent $425,591 on campaign; Picture 2, J. WILLIAM MIDDENDORF . . . gives to Warner opponent.