MERIDIAN, MISS., DEC. 3 -- White House Chief of Staff John H. Sununu resigned today, ending a stormy three-year tenure as President Bush's most powerful adviser on domestic policy and politics.

In a handwritten letter of resignation abruptly given to reporters after Bush had finished making a speech here, Sununu said he did not want to become a "political negative" for the president and a "drag" on his chances for reelection. Only two weeks ago Sununu said he expected to remain as chief of staff through Bush's entire term and run the reelection campaign from the White House.

Sununu will assume the post of counselor to the president until March to help in the transition period, and then will leave the government. Bush said he would have a new chief of staff "soon" but declined to say whether he has made a choice and who it might be. Speculation centered on Transportation Secretary Samuel K. Skinner but White House officials said no job offer had been made as of tonight. Aides warned that the president has a propensity to make such choices in secret and that other candidates could be under consideration.

Talking with reporters aboard Air Force One en route back to Washington, both Bush and Sununu struggled to portray Sununu's departure as the chief of staff's decision. But White House officials said it had become almost inevitable after the president's son, George W. Bush, made clear to Sununu last week that he had become a political liability.

"I knew the rules of the game when I came to town," Sununu said. "I always told him {Bush}, if I can serve him best by being in the job, I want to be in the job. And when that became a political burden, I'd be willing to leave."

Sununu said that at a point where Bush is beginning a reelection campaign, "he doesn't need an extra political target," and added, "I'm not going to be here to cause a problem for the president."

Conservative Republicans who had viewed Sununu as an ally and soulmate praised him effusively today. But privately, some Republicans -- including conservatives -- expressed relief that the resignation, which they saw as inevitable, has cleared the way for a much-needed shakeup within the Bush White House.

Democrats tended to direct their fire not at Sununu but at Bush himself, arguing that the chief of staff could not be blamed for the president's own shortcomings or troubles in the economy.

Sen. John H. Chafee (R-R.I.) summed up the bipartisan view of a city accustomed to seeing subordinates suffer for the sins of their superiors. "If you read 'The Prince' by Machiavelli, it's the courtiers who get jettisoned when times are tough," Chafee said. "That's the way the system has worked for years."

Bush, looking rueful and uncomfortable as he talked to reporters with Sununu at his side, described the resignation as a "compatible parting of the ways" and avoided a direct question on whether he had asked his chief of staff to go. "The timing was his decision," the president said, calling the resignation "a class act" by Sununu.

Today's announcement, made by White House press secretary Marlin Fitzwater beneath camera scaffolding in an electronics warehouse, capped an extraordinary two weeks in which Sununu's support within Republican circles outside the White House and among his own aides took a precipitous drop.

Sources close to Bush said Sununu had never recovered the president's confidence after the controversy last April over his extensive use of government planes for his personal business. A series of missteps on domestic issues this fall and Bush's sinking approval rating, attributed mostly to the lagging economy, were blamed in part on Sununu's operation of the White House.

Inside the White House, Sununu was portrayed as intent on fighting his removal until last week, when even top aides such as deputy chief of staff Andrew Card were said to have told him the tide had turned against him. Washington this week was immersed in speculation over scenarios for Sununu's departure that included shifting him into another high post, but he ended up simply departing. His letter to Bush said he would go into the private sector.

Bush owed Sununu a special debt of gratitude for his help, as governor of New Hampshire, in winning the state's critical primary in 1988. In recent days Sununu had made a final effort to save his job by asking Republican leaders, old Bush friends and Cabinet members to intercede for him. One of those approached by Sununu said he told him the effort was "unseemly" and was further hurting the president.

The White House recently had seemed almost frozen as aides followed the unfolding drama of Sununu's fall from grace and Bush's struggle to recover from serious political setbacks and go back on the offensive. Many advisers warned Bush, according to GOP sources, that Sununu's departure was necessary to clear the way for a structured campaign team and a better White House political strategy.

According to Fitzwater, Sununu had a series of conversations with aides and supporters but told Bush on Monday he would submit his resignation today. He gave Bush the five-page handwritten letter of resignation aboard Air Force One as the two flew to Florida for the first stop of today's trip. Fitzwater said the two spent most of the two-hour flight together in the presidential cabin. The president's official letter of acceptance was typed on the same flight and reporters were handed the letters several hours later.

In his letter, Sununu described a White House that was "an unbelievably fun place to work" and an "singularly unique" atmosphere of "friendship, caring and irreverence," a description at odds with the tense, fearful climate many aides described. Sununu said he had intended to remain in his post "as long as I could contribute to your success and help deal effectively with both the issues and the arrows." Until recently, Sununu said he was convinced he was an asset to Bush "even with the distorted perception being created."

But entering a campaign year, such perceptions "can be -- and will be -- converted into real political negatives." he said, and added, "I would never want to not be contributing positively, much less be a drag on your success."

Until the end, some conservatives were pleading for Sununu to stay.

"Seems to me if I were George Bush, I wouldn't want to cast away the best liaison I have to the conservative wing of the party," Rep. Vin Weber (R-Minn.) told reporters at a Capitol Hill news conference he held with another prominent conservative, Rep. Henry J. Hyde (R-Ill.), just hours before Sununu quit.

After the resignation, Hyde, who shared Sununu's strong feelings against abortion, saying he was "saddened."

"Many of us trusted him and felt comfortable with him politically and philosophically," Hyde said. "His intelligence, candor and loyalty will be missed."

But even on the right, there was not unanimity, and that may have been Sununu's final problem. Having alienated even conservatives with his abrasive style and his support for the budget agreement negotiated with Congress last fall and the tax increases that resulted from it, Sununu got only belated support from what should have been his natural constituency.

"Once he began treating criticism as if it were treason, some conservatives started questioning how useful Sununu was to conservatism or the president," said Burton Yale Pines, vice president of the conservative Heritage Foundation and one of those whose phone calls Sununu stopped returning.

Gary L. Bauer, a former Reagan administration official and president of the conservative Family Research Council, said many conservatives felt bound to defend Sununu "as the most visible conservative in the administration" who was frequently the target of liberal attack and who often took tough stands on behalf of causes dear to the right.

But Bauer said Sununu suffered from "an abrasive style that made him unnecessary enemies," even among his allies.

Democrats -- many of whom had privately refrained from criticizing Sununu because they felt him more an asset to their cause than to Bush's -- were quick to argue that Bush's problems transcended the question of who was his chief of staff.

"The political problems being experienced by President Bush relate to the recession, and to the economic policies that hurt America's working families, not the leadership of Gov. Sununu in carrying out those policies," said House Majority Leader Richard A. Gephardt (D-Mo.). "The American people recognize that staff people come and go; what matters is whether the president is prepared to change his economic policies. . . . "

Senate Minority Leader Robert J. Dole (R-Kan.), defeated by Bush in the 1988 New Hampshire primary in which Sununu played a leading role, issued a carefully worded statement that sought to be gracious without expressing any real regret that Sununu was gone. "No doubt about it, being the president's chief of staff is one of the toughest jobs in town -- you're a lightning rod for criticism, and no matter how well you do, you'll never please everyone," Dole said. "In my view, John Sununu did a good job -- he was loyal, and he served the president well. I worked well with John Sununu, and I wish him all the best."

Staff writers E.J. Dionne Jr. and Maralee Schwartz contributed to this report.

December 3, 1991 President George Bush The White House Dear Mr. President,

A little more than three years ago you asked me to be your Chief of Staff. I eagerly and appreciatively accepted.

Over these years it has been one of the most gratifying and satisfying experiences of my life to serve a President whom I admire, respect and will always consider a dear friend.

These have been amazing times for the world and the nation; they have been exciting and thrilling times for me. I am truly grateful for the opportunity to have been a part of it.

But most of all, from a purely personal perspective, I want to thank you for the fun we have had these last three years. In a way that will be very difficult for historians to capture, this White House was an unbelievably "fun place" to work. You, the Vice President, Scowcroft, Gates and I proved we could do very serious things well without taking the process or ourselves too seriously. I believe that chemistry, friendship, caring and irreverence was a singularly unique period for the Oval office, probably impossible ever to replicate. You were just great to let us do it that way.

I must also take this opportunity to tell you again how proud I am of the White House staff you allowed me to put together. They will eventually be recognized as the most talented, mutually supportive, cooperative team ever to serve a President. In fact, one of the challenges ahead of us will be to make very clear the significance of all you and they have accomplished in the domestic area as well as in foreign policy.

I have always said I wanted to serve as Chief of Staff as long as I could contribute to your success and help deal effectively with both the issues and the arrows. Until recently I was convinced that even with the distorted perceptions being created, I could be a strong contributor to your efforts and success.

But in politics, especially during the seasons of a political campaign, perceptions that can be effectively dealt with at other times can be -- and will be -- converted into real political negatives. And I would never want to not be contributing positively, much less be a drag on your success. Therefore, as we enter the contentious climate of a political campaign, I believe it is in your best interest for me to resign as Chief of Staff to the President of the United States effective December 15, 1991.

As much as I will truly miss the opportunity to continue to work in the West Wing with you and my friends there, I want you to know how strong and positive and upbeat I feel about doing this. I think you know that the responsibility and authority (contrary to the legends out there) never meant as much to me as the chance to assist you to be (and to be recognized) a great President. I intend to continue that effort as an ordinary citizen, with all the benefits that accrue to man and family in the private sector of our magnificent system.

I assure you that in pit bull mode or pussey {sic} cat mode (your choice, as always) I am ready to help.

I also want to thank Barbara and all the Bush clan for being such wonderful friends and strong supporters even during the toughest of days. Nancy and I and our family will always remember and cherish that kindness and friendship. I hope we will all have a chance to share a few laughs over the holidays.

Thanks again for the privilege of serving you and this wonderful country. It really has been great!!!

Sincerely and respectfully,

John H. Sununu