He was going to get a new campaign manager, Ronald Reagan said, twirling his glasses and speaking in that soft sincere way that has made him one of America's most familiar figures for some 40 years. They couldn't continue the way they were.

It was shortly after 1 o'clock in the morning, and for the second straight day his campaign was ending well after midnight. Reagan was standing in the aisle of his plane as it began its descent into a South Carolina airport. tHe glanced at the reporters stretched out trying to sleep. We wouldn't have to go on this way, he said, if they didn't write all those stories commenting on the supposed leisurely pace of his campaign.

The tone was light-hearted and the remark about his campaign manager was in jest, but Reagan has made his point. He was going from daybreak to the next dawn and they were the ones showing signs of fatigue.

Ronald Reagon will be 69 Wednesday. If elected, he will take office three weeks before his 70th birthday. He would be almost exactly the age at which Dwight Eisenhower, the oldest man ever to serve as president, ended his eight years in the White House.

Television, the instrument that catapulted Reagan into national political prominence years ago, is unkind to him today. Seen in person on the stump, Reagan retains a youthful look -- the figure slim, the appearance neat, the pompadour-style of his hair perfectly in place, the smile quick and radiant. But in that pitiless eye of the TV camera closeups his age shows through -- the lines around his eyes, the jowls, the so-called "turkey" neck of those approaching their 70s.

Watching his campaign last week, from New Hampshire to Alabama, something else came through. There's a certain hesitancy, a stumble here and there, that one doesn't recall from other Reagan campaigns. He blows his lines now and then, says boycott when he means blockade, mentions turning over surplus funds to his gubernatorial predecessor instead of successor, refers to dismounting from an aircraft instead of disembarking, and displays at times an embarrassing unawareness of events.

An example: Last Tuesday morning, when news broke about the dramatic escape of American diplomats from Iran, Reagan was enroute by motorcade to Springfield, Mass., where he was to give a luncheon speech and remain until late afternoon. Reporters traveling with him learned of the development during the luncheon from calls to their desks or over radio.

But more than eight hours later, in West Orange, N.J., when reporters had the first opportunity of the day to question Reagan, the candidate knew nothing about the story that had led all the network TV programs and provided the banner headlines for all the late newspapers.

This was a staff fumble, a failure to make sure the candidate is quickly briefed on news he should know and be prepared to respond. And the occasional slips of the tongue are the kinds that can plague any politician. Nor do these add up to evidence that will be examined in Ronald Reagan's political obituary; Reagan has demonstrated amply before that reports of his political demise invariably are premature.

He still speaks to the last solid cadre of true American political believers, determined, motivated, zealous, confident in their absolute correctness. If the country is moving to the right, if flag-waving obviously is back in vogue, if communism once again is everyone's enemy, who bears better red-blooded credentials to lead the patriotic revival than Reagan? His campaign swings up and down the East Coast these days are designed to mobilize the faithful, not at this point win converts.

Since losing the Iowa caucuses two weeks ago, Reagan has reverted more to the old hard-line rhetoric of his past. He speaks of appeasement in the White House, warns of Godless communism, calls for American moral and military rearmament, quotes MacArthur's dictum "there is no substitutue for victory," and pledges "there will be no more abandonment of friends by the United States of America."

Defeat has prompted Reagan to move aggressively to rally his natural constituency, the ideological conservative right, just as Edward Kennedy's fall has propelled him to the liberal left. Now Reagan's campaign pace intensifies, he attacks more harshly, and he continually drops remarks about how far he's traveled that day and how long a schedule remains ahead. He makes no complaint; his words serve to dispel the great doubt that hangs over this, his third, race for the presidency: age.

Still, traveling with Ronald Reagan today brings a sense of being oddly apart. He sticks to familiar territory and politically familiar faces -- the Elks Lodge, the fundamentalist university students, the Italian-American evening rally, the small-town high school auditorium event with pom-pon girls in straw hats decorated with red-white-and-blue robbons, the community luncheon where the walls are festooned with the old "Go get 'em, Dutch" posters and where bags of balloons are hung from the ceilings -- but the old fire seems lacking. As in the past, hardly a black face stands out in the crowds. The groups are with him, no doubt, but for most cases without their remembered passion when he delivers up his choice red-meat lines.

For Ronald Reagan's legions, four more years appears to have tempered some of their ardor.

Even Reagan's staff descriptions of his campaign are couched in stilted language out of syne with the political campaign terminology of the '80s. Reagan, in this self-described sense, doesn't campaign. He tours. For instance, last week's trip advisory was for "Tour No. 7."

His press release talks about "the tour" going by "motorcade" and "the tour" spending the night and "the tour" returning to Los Angeles.

Seeing the tour perform on the road leaves other strong impressions.

The first stop, Gilford, N.H., a frost night, the parking lot outside the school filled, the crowd inside waiting patiently, every seat taken, on stage, a group of New Hampshire conservatives.

One by one, they take the podium to prepare the way for the candidate.

William Loeb, publisher of the state's dominant newspaper, The Manchester Union Leader, for years a voice of the militantly radical right, tells the audience they don't know how desperately weak America's defenses are, "Just imagine the worst and it's worse than that," he says.

He dismisses Reagan's Republican opponents by saying Howard Baker gave away the Panama Canal, Big John Connally wants to give away Israel to the Arabs and George Bush is the candidate of the self-appointed elite in the nation, the same group that controls most of the newspapers in the East: if Bush scratches his nose, it becomes a plus in those papers. He spins out the webs of the old conspiracy theory that has the liberals manipulating America.

An old woman, with classically snow-white hair, moves forward and reads a poem she's written for the occasion. It's about Reagan: He's a man And he stands Ten feet tall, Though some folks Say he's too old, And that's a lie . . .

She ends, to applause, by saying: "a wise man, you betcha, though he's not 54."

More warmup speeches, and then another elderly woman moves forward to give the final introduction. He's an American, she says. He loves America. He can restore the America we once had. She's frail and earnest and she pronounces her words with careful precision, much in the manner of the old high school elocution teacher. "I present Ronald Reagan," she says, calmly, deliberately, "the most qualified of all the candidates to serve as the next president of the United States of America."

The high school band strikes up "The Stars and Stripes Forever." From the back of the auditorium, flanked by his wife, the candidate enters.

Ronald Reagan once said the worst movie he ever made was "The Killers," the film adaptation of the Hemingway short story. It was also the only time Reagan ever played a villain. All the rest of his career he always played the good guy.

In his political career, no matter how bellicose his words, Reagan still plays the decent, quiet, aw-shucks, dedicated American. When we walks into the lights, he cocks his head to the right and looks up as if surprised to see all these people there, waiting for him. As he takes his place on the stage, a New Hampshire official shouts out to the auudience, "Iowa -- hell!" Reagan slaps his knee, throws back his head, and gives a great guffaw. h

Reagan the speaker remains the Reagan of old. He begins, "I am more than happy," stops, as if he's lost his place or thought of something else; then he turns to the old woman who introduced him and says he's been made speechless by her remarks. He's going to get a copy of what she said so he can read it "when things are going a little rough and I'm down." Invariably, he begins his addresses by saying something similar about the person who introduces him.

Much of the Reagan message is familiar -- the bureaucratic tangle in Washington, the shackling of industry by government regulatios, the stifling of free enterprise. Thrift, frugality virtue. Carter's made a mess of things -- in 36 months he's tripled the inflation rate, raised interest rates to the highest point since the Civil War (this becomes the War Between the States in the South), driven the value of the dollar to its lowest point. As for the Democratic presidential contenders in general, well, Jerry Brown's on every side of every issue, Ted Kennedy's on the wrong side of every issue, Jimmy Carter doesn't know what the issues are.

These problems, though, are insignificant, Reagan says, compared to "the damage done our national security." He gets progressively tougher on foreign affairs and the Soviet threat as he campaigns. In a passage that draws some of the strongest applause, he says:

"The president said we must ratify the SALT II treaty because no one will like us if we don't. He said we should give away the Panama Canal because no one would like us if we didn't. It is time to tell the president: we don't care if they like us or not, we intend to be respected throughout the world."

That is vintage Reagan. But how, exactly, this respect is to be achieved remains vague. A strain of simplicity and contradiction runs through much of his basic message.

Before the same audience, he can urge that there "be no more Taiwans," and yet say he thinks the mainland Chinese can be converted from communism. He can call for greater defense expenditures and tax cuts; for a strengthening of the economy and the elimination of the minimum wage; for putting pressure on the Soviet Union to remove its troops from Afghanistan by blockading Cuba; for saying the government is to blame for inflation and the government can make it go away; for calling for the establishment of American military bases in Pakistan when the evidence from that country is its leaders are opposed to them.

And Reagan can be capable of flatout misstatements of facts.

Thus, in every address last week he said:

"Arriving in Warsaw in 1977 President Carter got off the plane to announce to a startled satrap who rules that country on behalf of the Soviet Union, 'Our concept of human rights is preserved in Poland.' What concept of human rights can that be? Would he like to explain that to millions of Polish-Americans who know better . . .?"

Carter never said any such thing.

To those who hear him, the literal accuracy of his words probably are not the point. Reagan summons them to one last effort on his behalf. He tells a story before them, choking and actually showing signs of tears at the end, that unintentionally addresses his own political condition in 1980.

A World War II bomber, damaged by flak, is limping back to its base after a run over Germany. As it descends over the English Channel it becomes clear the plane will crash. The pilot orders his crew to parachute. A machine gunner, riding in the bubble below the plane, radios back that the flak has made it impossible for him to open the escape hatch.

The pilot replies, "Don't worry, son, we'll ride this one down together" -- and down they go into flames and glory. "That's the kind of America I want," Reagan calls out, in halting tones.

The questions for Ronald Reagan today are whether those loyal legions will stay with him to the end, and if so whether they will be able to avert a final crash.