A specter is haunting the Republicans' enjoyment of the steady slide in Jimmy Carter's popularity: the prospect of a replay of their 1976 nomination battle between Gerald R. Ford and Ronald Reagan.

The meeting here last week of Republican state chairmen and national committee members alternated between waves of euphoria at the chances of regaining the White House and despair at reopening the intra-party wounds with another round of Reagan-Ford battling.

"It would be awful," said Clarke Reed, the Mississippi national committeeman. "A pair of 69-year-old-men refighting the battle of the past. Reagan would win this time, but who needs it"?

Reed is exaggerating slightly. The former California governor would be 69 when the next Republican national convention rolls around, but the ex-president would be only a sprightly 67.

But there is no doubt that many party leaders, including some who are not much younger than Reagan or Ford, look with dismay on the prospect of a rerun of 1976.

New Jersey National Committeeman Bernard M. Shanley, an Eisenhower-era veteran who is a long way from the conservative Reed in the GOP spectrum, toyed with the idea of introducing a resolution here calling on Ford and Reagan to clear the way for younger candidates. But he dropped the idea as an exercise in futility.

And "futile" is what advisers to both men say such advice would be. Reagan, who has maintained a personal political organization and a heavy schedule of speeches since his narrow loss to Ford in Kansas City two years ago, is reported by aides almost certain to announce his presidential "exploratory committee" in February or March.

"I would say it is as close to certain as anything can be that he will be a candidate before the snow flies in the Sierras next winter," said one of his top political lieutenants.

As for Ford, his intentions are less fixed, but those who served in his administration and held senior places in his 1976 campaign are unanimous in describing him as determined to deny Reagan the 1980 nomination - if he can.

"Ford is very reluctant to drag his status as the ex-president through the primaries," said one adviser. "But he will do whatever is necessary to keep Reagan from taking control, even if it means running again himself."

It is that prospect that appalls some Republicans and sours what they see as the otherwise delightful prospect of running against a president whose problems seem endless. "I keep thinking," said one GOP pollster, "that something has got to come along to give him [Carter] a lift, but nothing does. Maybe he's jinxed."

Others, more cautious, give Carter a year to dig out of his troubles. But the anticipation of a 1980 victory was strong enough that it dominated most of the corridor talk at a GOP meeting ostensibly focused on final plans for the midterm campaign this fall.

The distaste for another Reagan-Ford battle reflects more of a fear of intraparty strife than if it does a personal dislike for either man or an enthusiasm for other candidates.

That is particularly strong among Republicans from states where the scars of the 1976 primaries are still visible.

"I'm tired of both of them," said Bill Taylor, the GOP chairman in Florida, where Reagan and Ford staged one of their main knockdown-dragout fights in 1976. "We've got plenty of candidates to choose from, so why do we need that again?"

A Nebraska party leader, who said she had hoped for a Ford-Reagan ticket in 1976 and is still angry at both men for refusing to resolve their diffrences at the convention, said, "They cost us the White House in 1976 and I don't think they should be allowed to do it again."

National chairman Bill Brock and other influential party officials from the past decade confirm that they have been approached often to see if they could dissuade Reagan and Ford from running again. Brock says it would be "out of the question" for him to undertake such a mission, and others are doubtful that any such message would be heeded.

There is barely more reason to believe that other candidates could preempt the field, even though therewill be many who will try.

On the conservative side, Rep. Philip M. Crane (R-III.) was here spreading the word of his availability. Crane, 47, a spellbinder who supported Reagan in 1976, reportedly will file as a presidential candidate with the Federal Election Commission within the next month.

Crane's early move is seen in part as an effort to dissuade Reagan from running. But conservatives also say they think the congressman is trying to establish priority for himself in a growing field of younger conservatives who have their eye on the presidency in 1980 and future years.

That field includes Rep. Jack Kemp (R-N.Y.), co-author of the tax-cut plan that has become the centerpiece of the 1978 GOP congressional campaign; Sen. Orrin G. Hatch (R-Utah), a leader in the battle against labor law revision; Sen. Paul D. Laxalt (R-Nev.), Reagan's 1976 campaign chairman and Senate floor strategist on the Panama Canal treaties; and Sen. Bob Dole (R-Kan.), Ford's 1976 running mate.

According to John P. East, the North Carolina national committeeman and a staunch 1976 Reagan supporter, there was "quite a bit" of support expressed for Crane, Kemp and Hatch at an informal caucus of about 25 conservatives members of the national committee here Thursday.

"There was quite a little feeling," East said - noting that he personally did not share it - "that since Reagan will be 69, maybe we should turn to a new standard-bearer."

But he said that talk ended, for all practical purposes, when Michael B. Montgomery, the California GOP chairman and a Reagan loyalist, said flatly, "Don't count Reagan out."

Montgomery later commented in an interview that he thought the age issue was "being raised as a bugaboo and is not a serious factor."

Except for Crane, most of the conservative favorites in Congress are expected to defer to Reagan, if the Californians makes his anticipated move. Two conservative former treasury secretaries, E. Simon, are also poised in the presidential wings, but neither appeared to have a large fan club among the party leaders here.

The situation among the moderate Republicans is somewhat different. With at least tacit support from Ford, George Bush has been traveling the GOP banquet circuit seeking support for an early 1979 presidential effort. As a former national chairman, Bush is personally popular among the national committee members.

But his speaking appearances drew mixed reviews. He was reported as a "hit" in two Midwestern states, but a key California Ford backer from 1976 said a recent Bush speech there was "about 1.5 on a scale of 1 to 10."

Senate Minority Leader Howard H. Baker Jr. (T-Tenn.) has a reelection campaign to worry about this year, and will do only limited out-of-state campaigning, aides here said. They said Baker will seek reelection to his leadership post in January and begin exploring the presidential race seriously next winter.

A third major potential candidate from Ford's wing of the party is Illinois Gov. James R. Thompson Jr. Like Baker, he has a reelection campaign on his hands this year, and is unlikely, in the view of those who know him, to plunge immediately into a presidential race in early 1979, whether or not he decides ultimately to seek the 1980 nomination.

While others, including Sen. Lowell P. Weicker Jr. (R-Conn.), Rep. John B. Anderson (R-III.) and Govs. Robert D. Ray of Iowa and William G. Milliken of Michigan are discussed as hopefuls, there is a belief among many past Ford supporters that the polls a year from now will still show Reagan and Ford as the major contenders.

At that point, they believe, Ford will face a difficult decision - whatever to gear up a campaign for himself or leave it to others to try to block Reagan's path in the primaries.

Ford is described by those who met with him recently for political strategy talks in Vail. Colo., as being in a somewhat ambivalent frame of mind.

He is, they say, increasingly critical of Carter's performance as president and is increasingly convinced that Carter will be beaten in 1980.

Carter's problems have improved both the public esteem for the former president, as reflected in the polls showing him well in front of the incumbent, and Ford's own self-confidence.

"There's no doubt in my mind," said one of the Ford advisers, "that he would like to run against Carter and go back to the presidency."

At the same time, these sources say, Ford's bitterness toward Reagan, which began in their 1976 contest, has increased, not diminished, with the passage of time.

Weighing against this, they report, is Ford's disinclination to jeopardize his standing as a popular ex-president, enjoying bipartisan esteem, by engaging in a protracted personal battle, through more than 30 primaries, against a formidable foe like Reagan.

If enough of his former supporters urge him to stay out, either because they think Reagan would beat him or because they fear the consequences for the GOP of another Reagan-Ford fight, then it might affect his decision, these advisers think.

But those cautions may go by the board, they say, if Ford's competitive instincts are provoked. And, intentionally or not, the Reagan camp seems to be provoking them.

When Lyn Nofziger, Reagan's political lieutenant, was asked about the wish expressed here to avoid another Reagan-Ford battle, he said, "My answer is very simple: just keep Jerry out."