Retired Adm. Bobby Ray Inman said yesterday he had asked President Clinton to withdraw his nomination to be secretary of defense and cast himself as a victim of "modern McCarthyism" practiced by newspaper columnists and Republican political opponents.

Inman, a 62-year-old Texas businessman who has held top national security posts in Democratic and Republican administrations, explained his withdrawal in an extraordinary news conference in his home town of Austin, Tex. He attacked the ethics of New York Times columnist William Safire and said Safire had recruited Senate Minority Leader Robert J. Dole (R-Kan.) to launch a partisan effort against him.

"I sense elements in the media and the political leadership of the country who would rather disparage or destroy reputations than work to effectively govern the country," Inman wrote in a letter to Clinton dated almost two weeks ago.

But a formal process to name a new nominee was launched only on Monday, and the tone of Inman's surprise news conference stunned many at the White House and in senior levels of government. Vice President Gore informed Defense Secretary Les Aspin of Inman's decision Monday night, officials said, and obtained a commitment from him to remain on the job until a successor can be named.

The Inman decision deals another blow to the Clinton administration's efforts to shore up its national security team and raises the question of whether the White House, eager to replace Aspin, did not probe Inman's state of mind sufficiently when he was being pushed to take the post in mid-December. One senior official said Inman "did express a lot of reluctance to leave Texas and reenter the fray" but added, "I don't think we can be blamed that he is so thin-skinned."

A senior official said that Inman was "skittish" from the outset about the media atmosphere in Washington and gave the White House signals early this month that he was having second thoughts. "This was a guy who knew how to play the game and thought he could play the game," said one person who talked to him in this period. "Only he discovered that the game had gotten a lot harder and a lot hotter."

Inman, in his letter released by the White House and in a long, bitter news conference, laid out a sequence of media events that he said led to his conclusion he did not want to return to public life. "I looked at the prospect of being one where it was constantly negative every day and decided that's not how I want to spend the next years of my life," he said.

Inman used the news conference and a string of interviews afterward to lay out his charges. He described a critical editorial page cartoon in The Washington Post a few days after the Dec. 16 announcement of his selection, a New York Times story critical of his operation of defense contractor Tracor Inc., what he saw as a defensive White House leak of his failure to pay Social Security taxes on a household worker and, finally, a "vitriolic attack" by Safire.

At the same time, however, Inman was getting widespread favorable coverage of his years in government and of his potential as defense secretary. One White House official said of the coverage in the two weeks after his selection, "With the exception of Janet Reno, no nominee has been so well received in the media."

And the Republicans Inman cited yesterday as poised to attack him in December were mostly favorable in comments about him then. Dole, for example, called him "a very good person for the job" and other Republicans were generally favorable.

But Inman did not see it that way. "I should have been able perhaps to rise above and see all the glowing words and not focus on the ones that I thought were unfair or distorted," he said, "but I couldn't."

Inman said he was told by Republican sources that Dole and Sen. Trent Lott (R-Miss.) planned to "turn up the heat" on his nomination by questioning Inman's failure to pay the Social Security taxes or his operation of Tracor.

Dole, in a news conference in South Carolina, flatly denied he was planning a partisan attack on Inman. "I have no idea what's gotten into Bobby Inman," he said, "Admiral Inman's letter doesn't make any sense to me." He said barring something unforeseen, the nomination was in no trouble and that his main area of concern was a difference over policy -- whether defense was being cut too deeply.

Lott had a similar reaction. "I am floored by the bizarre press conference," he said, repeating a word used by numerous administration aides and congressional figures of the hour-long Inman performance, broadcast live on Cable News Network. Said one White House aide: "Most of us were glued to the tube, our mouths open in shock."

In an interview last night, Inman said he believed he had received reliable information about Dole's intentions, but that he was prepared to accept Dole's word that there wasn't any deal.

In his most specific personal attack, Inman said Safire, a conservative columnist who served as a speechwriter for Richard M. Nixon, has had a long vendetta against him. He said that vendetta began when Inman, in 1981, took actions that limited Israel's access to certain U.S. intelligence data.

He cited a Safire column as a turning point in his decision. That column accused Inman of being a media manipulator, a tax "cheat," a "flop" as a businessman and anti-Israel. Those characterizations, Inman said yesterday, "from a man who has hidden his own plagiarism by an out-of-court settlement with sealed documents does not . . . put him in a position to frame moral judgment on any of us. . . ."

A New York Times statement said the incident Inman apparently was referring to occurred "about 35 years ago" when Safire was working with a public relations firm, and that Safire had not stolen any material from another writer.

In an interview last night, Inman backed away from his allegation, saying he had "no documentation" and that the version provided by Safire and the Times "may well be accurate. I therefore would apologize."

Inman suggested that while he believed he would be confirmed, the scrutiny of the news media and the Senate in the confirmation process, and what he sees as constant attacks on public officials by columnists in particular, made service unattractive to him.

Senior White House officials said yesterday they knew of no reason other than the ones Inman enunciated in his news conference for the withdrawal, and said quitting was Inman's decision. Two administration sources said the FBI background check on Inman provided nothing that would disqualify him for the post.

Inman, asked at his news conference if further damaging information about him was about to emerge, said "no, none," and cited a string of allegations made about him over the years that he said were not new and had previously been put behind him. One was that he was somehow connected with the Lyndon LaRouche organization because he met with him while working for the CIA after LaRouche had taken a foreign trip.

Another, he said, was that he was homosexual because he had refused to fire a gay employee at the National Security Agency. "We dealt with that back" in 1980-81 "when to deal with them I volunteered to take the polygraph at the CIA, didn't need to, and I passed it," he said.

Inman described himself as growing increasingly worried in the two weeks after his selection about attacks during his Senate confirmation hearings and as having conversations with Washington friends who warned him of Republican intentions. White House officials said yesterday Inman had begun raising those concerns with them during the first days of the new year and on Jan. 6 he called deputy White House counsel Joel Klein to say he was withdrawing.

A senior official said the White House has done little since then to find a replacement for fear the news would leak out and upset the president's nine-day trip to Europe. Inman's call to the White House came on the day Clinton's mother died, two days before the European trip.

The timing of the announcement put Aspin in a particularly awkward position. Senior Pentagon officials said he had spent much of last weekend working on his farewell speech and preparing for a series of ceremonies that were to begin today.

Administration officials said White House Chief of Staff Thomas F. "Mack" McLarty would lead the replacement search, as he had when Inman was selected. William J. Perry, deputy secretary of defense. and John M. Deutch, undersecretary for acquisition, were being prominently mentioned as replacements, but senior administration officials said no announcement was "imminent" and one said the president "has several people he wants to talk to."

Staff writers Helen Dewar, Howard Kurtz and John Lancaster contributed to this report.