The scandal is the campaign's prologue.

As the curtain opens on 1988, a spectacle other than the orderly exit of the regal Ronald Reagan is revealed. It is more like a fire in the zoo during which the cage doors have come unhinged and the beasts can be glimpsed prowling amid the smoke. "We have seen this before," says Patrick J. Buchanan, who may himself become a presidential candidate and who, in any case, is intently exploring the possibility.

As Reagan's communications director, during the Iran-contra arms scandal, Buchanan is returning fire from a windowless office in the White House basement. (Actually, he has a wooden window frame hanging on a nail on the wall.) "What liberalism and the left have in mind," he wrote in the Dec. 8 Washington Post, "is the second ruination of a Republican presidency within a generation."

This is the Buchanan moment, when the ranks of sunshine conservatives have dwindled, the moment for the foul-weather friend. Buchanan, the presidential aspirant aborning, is a man for one season -- the mean season.

On Sept. 26, 1973, Buchanan, then a speech writer for Richard Nixon, appeared before the Senate Watergate committee. As far as he was concerned, the committee was on trial. "The mandate that the American people gave to this president and his administration," said Buchanan, "cannot and will not be frustrated or repealed or overthrown as a consequence of the incumbent tragedy."

After Nixon's resignation, Buchanan called Watergate "the lost opportunity to move against the political forces frustrating the expressed national will," and summarized its lesson: "To effect a political counterrevolution in the capital . . . there is no substitute for a principled and dedicated Man of the Right in the Oval Office."

He stands out so starkly because he does not hesitate to utter the forbidden. He has divided the universe into the loyal and the disloyal. And he has savaged his own party's "establishment" as treacherous: "What a classic portrait in ingratitude|"

Like another presidential assistant -- one of his "heroes," Lt. Col. Oliver North -- Buchanan frequently marches to his own drummer. His Post essay was unauthorized because he feared it might be suppressed. And his high-noon peroration Monday at a conservative rally in Lafayette Park -- "You will not bring this president down|" -- was also unauthorized. While he demands unquestioning fealty to the president, he eludes control himself. By this, Buchanan unintentionally illustrates the Reagan style of presidential management, which has helped bring down the sky on the White House.

After his performance in the park, a senior White House official said that Chief of Staff Donald Regan was weary of Buchanan's "extracurricular activities" and would be delighted to have him run for president, if it meant that he left the White House soon.

Still, Buchanan is no more a Reaganite than he was a Nixonite. "The greatest vacuum in American politics," he says, "is to the right of Ronald Reagan." Ultimately, he is loyal to an ideology, not a man. The "Man of the Right in the Oval Office" can always be replaced by another, even farther right -- perhaps even Buchanan himself.

Inhabiting the Oval Office is an idea Buchanan is seriously contemplating. Ironically, the "miserable, carping critics" he decries are preparing the ground for his candidacy. Since Reagan's reelection, the right has vainly advanced a series of issues, from contra aid to "Star Wars," to elevate its fortunes. At last, Buchanan has struck gold: the breaking of Reagan by "the liberal claque on Capitol Hill" and the "attack dog" press. Reagan's fall might mean the right's rise, after all.

In an interview, Buchanan suggests that Republican primary voters are being "radicalized" by Reagan's ordeal, that "an explosion" is about to occur. And none of the Republican presidential hopefuls has expressed this primal rage. Why not the beast?

Already, many of the powers of conservative America are entering into a combination to materialize this specter: Orange County and Human Events; Conservative Caucus and the Manchester Union Leader; and Jesse Helms' Congressional Club.

Next week, they will convene here to render Buchanan advice and consent. "My advice is that he has to make a decision in the next two to three weeks," says Angela Bay Buchanan Jackson, his sister, the former treasurer of the United States and a prominent conservative activist.

The Buchanan for President movement began last June. It was then that Los Angeles television personality Bruce Herschensohn narrowly lost a GOP senatorial primary clogged with other conservatives. His campaign manager happened to be Angela Jackson. Residing in the Southern California redoubt of the right, where the careers of Nixon and Reagan had been hatched, Jackson was worried by the absence of an obvious heir. "The conservative movement needs a leader," she says. So she suggested that her brother mount his own campaign. He was ambivalent.

Soon, Herschensohn became an enthusiastic supporter of the Buchanan idea. "I'd be delighted if he ran," he says. Many of his campaign's prime movers, who had been drifting toward the candidacy of Rep. Jack Kemp (R-N.Y.), quietly and approvingly observed Buchanan.

By New Year's, with the Senate lost to the Democrats and the scandal lapping at the Reagan administration, the Buchanan idea had attracted new adherents.

"Coup D'Etat," screamed the headline across Howard Phillips' newsletter. The Conservative Caucus president was voicing the sentiment, held by many on the right, that the latest turn of events was nothing less than a seizure of power by ancient enemies.

"Within the Republican Party," says Phillips, "it's class war." The forces that had denied conservatives presidential nominations in the 1940s and 1950s, and opposed Barry Goldwater in the 1960s and Reagan in the 1970s, are still at bay, manipulating the present crisis to their own ends. In Phillips' formulation, the "Wall Street wing" is usurping what had been rightfully gained by the "Main Street wing." "It's going to have a cathartic effect on the future of American politics," he says.

For Phillips and other New Rightists, the Buchanan idea is a neat coincidence of conviction and self-interest. Throughout the Reagan era, many of the previously flush right-wing political action committees have gradually gone bust. "These organizations are in desperate financial straits," says one conservative leader. "Reagan has taken away their agenda. It's hard to rally the conservatives against the White House and the evil establishment. They need a new cause."

"Buchanan may be the Churchill of our times," says Tom Ellis, chairman of the Congressional Club, the direct-mail fund-raising operation that has been instrumental in the success of Sen. Jesse Helms (R-N.C.).

But Helms is not running for president. He has been unsuccessfully striving to be minority leader of the Foreign Relations Committee, not a cause to turn the wheels of his political machine.

But with Buchanan making the race, Ellis claims, votes would not be scarce. "Republican primary voters are a different breed of cat than the electorate at large," he says. "The mushball in the middle disappears. It pretty well starts to squeeze down to the right."

And the money, he supposes, would not be scarce either. "We raised down here $18 million for Jesse Helms for a Senate campaign. We're talking about a nationwide campaign, with more organizations than ours. With all the organizations working together, if you raised $12 million and got $12 million in matching funds, that would give the fellow $24 million. I don't see why we can't do that."

The Congressional Club would also provide the services of its executive director, Carter Wrenn, as Buchanan's campaign manager.

"If Pat were to make the decision, it would galvanize conservative sentiment overnight," says Rep. Philip Crane (R-Ill.), a former presidential candidate, who has held aloft the banner of the movement for decades. "Conservatives are wandering in the doldrums of indecision right now. They haven't gotten turned on by any of the candidates. Pat could cause that sentiment to get behind one candidate . . . He would have a leg up on money. Conservatives would give to a conservative candidate. Look back at the Goldwater candidacy; it's illustrative of what conservatives are willing to do if there's the candidate."

The New Right, Crane adds, hungers for a Buchanan campaign. "That would melt their butter," he says.

Moreover, he is sure that if Buchanan leaped he would land on a large base. "The same people who gave the Republican nomination to Reagan and supported me in New Hampshire are still there," Crane says.

In the Granite State itself, the Manchester Union Leader continues to hold sway, especially over conservative primary voters. "It would make it a heck of a lot more fun if Pat Buchanan ran," says Nackey Loeb, the Union Leader's publisher. "As I look at all the candidates who like to spend time in New Hampshire, if there were someone interested in carrying on {Reagan's tradition}, that would be the person for me. That might be Buchanan."

But her encouragement of a Buchanan candidacy should not be taken as an open endorsement. She still wants GOP supplicants to beseech her for the paper's blessing. "We're waiting and watching," she says.

For much of the last generation, Buchanan has programmed the conservative political rhetoric of the White House. He has been one side of Nixon, the whole of Agnew and Reagan without the smile.

He is also a television performer in his own right -- an essential Reagan legacy. If the GOP primaries, particularly the debates, become an expanded version of "The McLaughlin Group" (on which Buchanan starred), then he has the experience to do well. He has learned the lesson taught by Jesse Jackson that running for president means a lot of free national television time.

The scandal already has given him many forums: half time on ABC's "Monday Night Football," a segment of an NBC News special, frequent bites on "CBS Evening News." More important, the scandal has altered Republican presidential politics, hurting the obvious institutional and ideological successors. And Buchanan's outbursts have contributed to the crackup, much to his potential advantage.

If Reagan had smoothly sailed to the end of his term, conservatives would likely have endured 1988 in a mood of quiet desperation. The hallmark of the campaign would probably have been continuity, a theme that called for Vice President George Bush.

Bush attempted to ingratiate himself with the right while maintaining his standing among the regulars. But as Oliver North invoked the Fifth Amendment, Bush's effort to square the circle collapsed, along with his poll numbers. What Reagan had finally bequeathed him was the taint of scandal. The place of institutional successor was promptly filled by Senate Minority Leader Robert Dole (R-Kan.), who was carefully sidestepping around the prone presidency, under which lay Bush.

On the surface, the ideological successor appears to be Rep. Jack Kemp. But the conservative attraction to Buchanan is due in part to a lack of attraction to Kemp. With his arcane talk of the gold standard, he appears to many of them to be on a political lead standard. He makes complicated what they know is simple; he befuddles rather than galvanizes.

"Jack's appeal is supply-side economics and the Laffer Curve and a lot of stuff I don't understand," says Tom Ellis. "Buchanan talks about the Russians moving into Nicaragua and starting to push illegal aliens across our border by the millions. I can understand that."

"Jack Kemp has been out there for two years," says Angela Jackson. "He's gone from 7 percent to 7 percent. A lot of conservatives have gone with Bush, not a natural home. For whatever reasons, the conservatives are not comfortable with Kemp. He wants to be crowned. You have to have guts in this game. To let this campaign take its course without a conservative who can bring conservatives home means we'll go for four years without a solidified movement."

Kemp, for his part, has reacted to recent events by following Buchanan to the edge of the earth. "I've got to say, in all candor, bravo to Pat Buchanan," he announced on Jan. 5 on "The MacNeil/Lehrer NewsHour."

Buchanan, however, is hesitant to plunge into the campaign because he fears he may mortally wound Kemp, according to a source close to Buchanan. But the case will be strongly made to him by his advisers next week that Kemp is lifeless already.

Many conservatives are also increasingly disillusioned with the Rev. Pat Robertson, the television evangelist. His beliefs may be powerful enough to rebuke a hurricane, but not the Internal Revenue Service, which is auditing his Freedom Council for allegedly improper political activities. He is also caught up in a libel suit against former representative Pete McCloskey (R-Calif.) and Rep. Andrew Jacobs Jr. (D-Ind.), who claimed that Robertson used his father's position as a senator to avoid combat duty in Korea.

"Buchanan for Robertson is a trade up," says a prominent conservative.

"I think Pat Robertson is damaged right now," says Angela Jackson. "If he doesn't run it would be fantastic for us. Good heavens|"

Conservative history does not oppose Buchanan, and his personal story is the story of conservatism, or at least a large part of it.

He was overwound as a boy. Every night, his father William, an accountant, made him hit a punching bag 300 times. William had deserted the Democratic Party in 1936, the year of Franklin Roosevelt's greatest triumph. The household gods were Sen. Joseph McCarthy and Gen. Douglas MacArthur. At age 9, Pat was a caddy at Burning Tree Club for Richard Nixon.

Educated by Jesuits, he now feels that the Catholic Church went wrong when the prayer for the conversion of the Russians was replaced by a prayer for peace. At age 21, he was expelled from Georgetown University after pleading nolo contendere to charges of assaulting two policemen who stopped his car; he broke his hand.

Later, he graduated from Georgetown and earned a master's degree from the Columbia School of Journalism. He aspired to be like William F. Buckley Jr. He became an editorial writer for the now defunct St. Louis Globe-Democrat, frequently excoriating the Rev. Martin Luther King Jr. In 1966, he became the first full-time member of Nixon's campaign staff. He was known as "Mr. Inside" because he wrote the speeches designed for the hard-core.

During the 1972 campaign, Buchanan led the effort to besmirch the image of the Democratic opponent, George McGovern -- "tar him as an extremist," read one Buchanan memo. He urged Nixon to burn the White House tapes. His role in the White House campaign "Attack Group" prompted his appearance before the Watergate committee.

In the confusion immediately after Nixon's fall, Buchanan attempted to be appointed ambassador to South Africa, but President Ford refused to sign the paper that had already been approved by holdover Chief of Staff Alexander Haig.

The history of our times, as told by Buchanan, is a tale of betrayal. Nixon came into office as a man of "reconciliation and restraint," he wrote in 1973 in The New Majority. But "the liberal aristocracy . . . politically unprepared for the 'trauma of distasteful reversal' " broke the "armistice" he offered.

By the time he returned to government in 1985, his career as a columnist, speaker and television performer had earned him an annual income estimated at $400,000.

Within the White House, he urged Reagan to stand tall at the Bitburg cemetery. When House Republican leaders of the Conservative Opportunity Society told him of their support for limited economic sanctions against South Africa, he rebuffed them. He urged Reagan to stand tall.

In a March 1986 article in The Post, he wrote that the vote on contra aid "will reveal whether {the Democratic Party} stands with Ronald Reagan and the resistance -- or Daniel Ortega and the communists." In defense of Oliver North, he declared in a December speech: "It is not whether some technical laws were broken, but whether we stop communism in Central America."

For the right, Reagan's fall is the ultimate nightmare, a turn in the cycle of defeat far more serious than Nixon's. Conservatives loved Nixon for his enemies, but never fully trusted him. And when he departed there was an obvious champion to pick up the pieces: Reagan. Now the right is in pieces. That is what has led to the Buchanan for President movement.

In his own way, Buchanan posed the question facing the right in a February 1986 speech to the National Religious Broadcasters: "Whether President Reagan has charted a new course that will set our compass for decades -- or whether history will see him as the conservative interruption in a process of inexorable national decline -- is yet to be determined."

In the basement of the White House, Pat Buchanan is thinking about moving upstairs.