As Ronald Reagan sees it, the seeds of his victory in the Republican presidential contest were sown in the dark hours of defeat after the Iowa precinct caucuses last Jan. 21.

Talking to reporters in Los Angeles that night, Reagan tried to put the best face on his upset loss to George Bush. But Reagan knew that his frontrunning candidacy was tottering, and he was in a sour mood.

Chief of staff Erwin Meese recalls Reagan saying grimly to him the same night, "There's going to be some changes." What followed almost immediately was the abandonment of Reagan's above-the-battle, no debate strategy in favor of an intensely personall ground-level campaign that culminated in the candidate's stunning triumph in a Feb. 23 debate confrontation in Nashua, N.H.

"I guess I was probably at my lowest point after Iowa which everyone assumed would be automatic for me," Reagan said this week, one day after Bush conceded the GOP nomination to him.

"We knew that the eyes of the country would be on New Hampshire as far more significant than its size would warrant," Reagan said, "there was free time, open time, in my schedule and I demanded that we do more than had been originally planned in New Hampshire and that I campaign as I did the last time when I got 49 percent of the vote in 1976. I wanted to get out of the bus and meet the people and meet them where they were, and that's what we did. I think it set the course for what followed."

"I sensed for weeks before that, psychologically, Ron felt trapped," says Nevada Sen. Paul Laxalt, a self-styled Reagan "fireman" who is the former governor's closest link to the organized conservative movement. "He concurred in avoiding the Iowa debate but subconsciously he didn't feel right about it. When he changed, he was liberated and it enabled him to perform in New Hampshire."

History is likely to judge Reagan as the underrated front-runner of 1980. Though he held a wide lead in public opinion polls, Reagan's age, conservatism, and lack of foreign policy experience seemed heavy marks against him. Political strategist David Keene, who left the Reagan campaign for a bigger role in the Bush organization in February 1979, said early on that the nomination was "Reagan's to lose." There were many who expected Reagan to lose it.

Instead, Reagan won one of the most convincing victories of modern Republican primary campaigns.

Competing in 24 primaries against Bush and other Republican candidates, Reagan won 20 of them. Bush won only four plus the primaries in Puerto Rico and the Distric of Columbia, where Reagan was not entered.

Going into the now anticlimatic round of eight primaries on Tuesday, Reagan has received 5,104,000 or 57 percent of the 8,857,000 votes cast in the 1980 GOP primaries. Bush, his most persistent opponent, received 2,296,000 votes or 36 percent.

While there are some differences of interpretation on what was most significant for Reagan in achieving his victory, ther is broad agreement among deposed campaign manager John P. Sears and the men who replaced him on many of the key events and decisions of the campaign. Here is the way Reagan did it:

March 7, 1979, Washington -- A 365-member "exploratory committee" headed by Laxalt is formed in behalf of Reagan's candidacy. The announcement was routine but the decision that lay behind it was not. it was a tactic pressed by Sears and Laxalt to put off Reagan's formal declaration of candidacy as long as possible. "You can't lose the race if you're not in it," said Sears.

Sept. 17, 1979, San Diego -- Without much attention in the East, Reagan's forces at the California Republican Convention block an attempt by supporters of John B. Connally and Bush to change California's winner-take-all primary. The action virtually assured Reagan of the state's 168 delegates nearly one-sixth of the number needed for nomination.

Nov. 13, 1979, New York City -- in a nationally televised speech from the ballroom of the Waldorf-Astoria, Reagan becomes the last Republican presidential candidate to enter the race. The location of his announcement is even more important than the timing.

Even the fiercest critics of Sears credit him for giving Reagan a Northeast focus that helped make Reagan a truly national candidate. Sears is a former New Yorker who in 1976 tried vainly to unlock pro-Ford delegates for Reagan but was blocked by Nelson Rockefeller. With Rockefeller gone, Sears believed that Reagan could and should line up Northeast delegates in advance for his 1980 race. This estimate subsequently proved accurate when Reagan won the New York delegate primary on March 25 -- a month after Sears had been fired.

Jan. 4, 1980, Des Moines -- The first debate of the Republican candidates, especially Connally, make fun of Reagan's absence and put the front-runner on the defensive for the remainder of the Iowa campaign.

"Reagan was very much aloof at this time," recalls pollster-strategist Richard B. Wirthlin. "He was giving cameo performances, he wasn't staying in any state long enough to make an impact. His advantage was frittered away by the refusal to debate, which was viewed unkindly by Iowa Republicans."

Jan. 21, Iowa -- Sen. Howard H. Baker Jr. had called the Iowa caucuses the "functional equivalent of a primary." But it is the view of Meese and Wirthlin that no one in the Reagan campaign realized this until after the fact. "Reagan didn't have a presence in the state, we weren't well-organized and we didn't have an adequate intelligence system," says Wirthlin. "Bush was able to dump in a million pieces of mail and we didn't know it until after the election."

However, it was because the shock of losing was so great that Iowa became the key to victory. "It brought the whole campaign back to a world of reality," says Laxalt. "It enabled the governor and Nancy to campaign on a personal basis."

Feb. 6, Concord, N.H. -- Reagan celebrates his 69th birthday, the first of several such public events designed to defuse the age issue by publicizing it. Reagan is now well-launched into a grueling 21-day campaign organized and orchestrated by New England campaign manager Jerry Carmen, an ardent critic of the Sears front-running strategy. In December, reporters had mocked Reagan's "front walking" campaign. Now, a sign appears in the candidate's press room: "Free the Reagan 44."

Feb. 20, Manchester, N.H. -- Reagan debates six other Republican candidates at a time his polls show him a single percentage point behind Bush. cAnxious to do well, Reagan is nervous at debate time. "While I though him more uptight than he had ever been in a public forum, his forcefulness compared to Bush came through," says Wirthlin. But the popular perception was that it was at best a standoff.

"Bush did better in this debate than he had done in Iowa," Keene said. "We didn't think Reagan had done that well, and neither did the traveling press. But the voters watching it on television were making a different kind of comparison -- they were comparing Bush with this supercandidate they had heard about who had knocked off Reagan in Iowa. On camera, Bush looked pretty much like a guy who put his pants on one leg at a time like everyone else. And Reagan had started with the strongest base in the Republican Party, with the only question being, 'Was he up to it?' If he looked as good as anyone else, and he did, why not vote for him?"

Wirthlin believes that this debate was the key event of the entire campaign. His polls showed a 21-percentage-point gain for Reagan in three days, the massive voter shift that led to the Reagan landslide in New Hampshire.

Feb. 23, Nashua -- Many will always think of the Reagan-Bush debate as the night Reagan seized both a microphone as the nomination. "I paid for this microphone Mr. Green (sic)," said an angry but controlled Reagan to Nashua Telegraph Editor, Jon Breen, who had tried to have Reagan's microphone shut off.

The incident was the dramatic highpoint of a successful effort by Reagan and his strategists to portray Bush as an arrogant rival who wanted to keep Baker, John B. Anderson, Bob Dole and Phil Crane from joinging in the debate. Credit for the strategy must be shared by Sears and his aides, who negotiated the ground rules, and Carmen, who proposed the debate in the first place.

But the event turned out the way it did more because of the candidates than anything else. Reagan, usually at his best when aroused, stole the show while Bush seemed not to know quite what was going on. Later, Bush press secretary Peter Teeley, irreverent and accurate, reportedly told his candidate: "The bad news is that the media is playing up the confrontation. The good news is that they're ignoring the debate, and you lost that, too."

Feb. 26, New Hampshire -- Reagan defeats Bush nearly 2 to 1 and regains his status as front-runner. The afternoon of his victory he fires Sears, political director Charles Black and press secretary Jim Lake in a shakeup that in effect restored Reagan as head of his own campaign. Former Securities and Exchange Commission chairman William J. Casey is brought in as campaign director and Messe, whose Sears' attempt to fire triggered the timing of his own dismissal, becomes chief of staff.

March 4, Vermont and Massachuseets -- Anderson runs a surprisingly strong second in both states, finishing behind Reagan in Vermont and Bush in Massachusetts. The ultimate beneficiary, Wirthlin and Sears agree, is Reagan. Anderson's successful presence in the crucial early primaries makes it impossible for Bush to obtain a one-on-one test with Reagan until it is too late.

March 8, South Carolina -- Reagan wins another primary and knocks Connally out of the race. "If Connally had developed credibility, his vote would have come out of ours," says Wirthlin, "and in a multicandidate race this would have posed a danger." Reagan uses South Carolina as a stepping stone to sweep the Florida, Alabama and Georgia primaries against Bush the following Tuesday.

March 18, Illinois -- Reagan wins a key primary over Anderson and Bush by an impressive margin and takes an insurmountable lead for the nomination. Where he had won by confrontation in New Hampshire, Reagan managed to stay above the battle in a relaxed and witty Chicago debated while Crane and Bush worked over Anderson. Illinois demonstrated Reagan's ability to attract working-class, crossover votes, which the candidate now considers a key to his fall campaign.

"Illinois was the ratification of what we had been doing," says Wirthlin. From then on, Reagan was aided in media coverage, fund-raising and party organization by the assumption that he would become the nominee.

Reagan's chief obstacle now had become the profligate early spending of his own campaign, which before the first primary had used up two-thirds of the $17.6 million allowed under federal law.

The money crisis brought some of the Reagan managers close to panic because they knew the campaign would be hard-pressed to compete with Bush if he started winning a string of primaries. After the firing of Sears, Casey, treasurer Bay Buchanan and former California finance director Verne Orr put a stiff clamp on expenses, which restored the campaign to solvency.

It is true that Reagan entered the campaign with enormous assets. He was a celebrity and successful former governor who had campaigned for other Republicans at hundreds of fund-raisers, waged a hard battle for the nomination in 1976 and gracefully conceded at the convention.

But Reagan had to overcome doubts about his age and ability, an ill-advised Iowa strategy, a major staff shake-up in the middle of the campaign and serious money problems. That he did so is, in some respects, a tribute to past and present strategists and managers, but it is most of all a reflection of the candidate himself.

From the dark days of Iowa to the triumph of the Illinois debate and his subsequent victory, Reagan remained the chief asset of his own campaign. It was the failure of his original campaign team to recognize this that had caused Keene, at the time Reagan was ducking the Iowa debate, to quip accurately, "We had more respect for Reagan as a candidate than they did."

"There was no magic," said Wirthlin. "The candidate won the primaries." And Meese, agreeing, adds this thought: "All things considered, I think we did better than we had any right to expect."