In a harsh, often personal attack on his former Senate colleagues, John G. Tower says he was rejected as defense secretary last year because of partisanship by Sen. Sam Nunn (D-Ga.) and weakness on the part of Sen. John W. Warner (R-Va.).

Tower charges in a memoir scheduled for publication in February that the Senate refused to confirm him for the top Pentagon job largely for political reasons, not because of questions about his personal conduct. He accuses Nunn of blocking the nomination to enhance his presidential prospects. Tower also charges that Warner's "passivity and lack of focus" helped Senate Democrats win the battle.

In the book, entitled "Consequences," Tower again denies allegations of heavy drinking and womanizing that were leveled during the confirmation process. Tower says he quit drinking hard liquor years before he sought a Cabinet post, and contends that many of the charges against him were spread by his ex-wife, Lilla.

But the memoir includes biting descriptions of at least six other senators, including allegations of excessive drinking by one.

Tower charges that Sen. J. James Exon (D-Neb.) "has a reputation as one of the most excessive regular boozers in the Senate. . . . Exon drinks and drinks heavily." Sen. Ernest F. "Fritz" Hollings (D-S.C.) is described as "the Senate bully . . . a study in arrogance and pomposity." Sen. Robert C. Byrd (D-W.Va.) "has a tendency to resort to a flatulent indignation, which alternately amuses and annoys his Senate colleagues." Sen. John Glenn (D-Ohio) is "not the brightest guy in Washington."

All these descriptions are included in the galley proofs of Tower's book, a copy of which was obtained by The Washington Post. Arlynn Greenbaum, a spokeswoman for Tower's publisher, Little, Brown and Co., said that neither the company nor Tower had any comment on the memoir.

Although the book covers Tower's political career, including his years as a Republican senator from Texas, most of it deals with his nomination and ultimate rejection for defense secretary, which was the first political struggle of George Bush's presidency. Tower blames his downfall primarily on Nunn, chairman of the Senate Armed Services Committee, and Warner, the panel's ranking minority member.

Tower charges that Nunn, considered by many the Senate's leading expert on defense issues, was jealous of his knowledge of the subject. Tower chaired the Armed Services Committee before Nunn.

But Tower alleges that Nunn's primary motivation was to damage Bush's credibility and to enhance his standing in the Democratic Party. Once the fight began, Tower says, Nunn "was far from shore, and he was afraid. . . . Nunn was out to win, and he was determined to do whatever was necessary to accomplish his objective."

Nunn was unwittingly abetted by Warner, Tower charges. As ranking Republican on the committee, Warner was in charge of shepherding the nomination through the Senate. But Tower says Warner was "painfully slow on the uptake" and refers to him as "a wholly owned subsidiary of Sam Nunn."

"John suffers from a debilitating political weakness: He wants to be liked by everyone," Tower wrote. "His passivity and lack of focus had been handicaps since the beginning of the confirmation process."

Of the senators singled out for criticism by Tower, only Warner would comment. "No less than 20 senators were taken to the White House for personal meetings with the president, and not a single vote was changed," Warner said. "How the hell am I supposed to protect {Tower} from that? . . . I sleep quietly knowing I did my job.

"If this guy wants to have some fun, I'm willing to give him some," Warner said. "You've got to know good old John Tower. This is just his Texas style of saying, 'Thank you, John Warner, for voting for me.' "