Presidential political strategists are launching a campaign to reelect Ronald Reagan that many of them foresee as a difficult, uphill battle to re-create the coalition that defeated Jimmy Carter four years ago.

"By any measure it's going to be a most difficult campaign," said Sen. Paul Laxalt (Nev.), general chairman of the Republican Party and a presidential intimate. "There are warts after four years, some of our majorities were razor-thin, and we're the minority party."

Across the country and in the high councils of the administration in Washington, the president's political strategists are worried about the difficulty of holding blue-collar voters in the recession-damaged Midwest. They are concerned about losing southern states because of a surge of black registration and about losing states everywhere because of the persistent "gender gap." Some of them also believe that the president's Central American policy could prove a severe political liability.

"It's going to be tough, damn tough," said White House deputy chief of staff Michael K. Deaver, who has been associated with Reagan since his first campaign for governor of California in 1966. "We have our work cut out for us in reforming the coalition or building a new one." Both Laxalt and Deaver, like other Reagan advisers, maintain that the president can overcome these formidable handicaps and be reelected.

They say that Reagan is rising in public esteem as the economy gathers strength, and voter surveys show him far higher than President Carter at similar points in their presidencies. Unlike every other elected president since Dwight D. Eisenhower, Reagan enjoys the prospect of an uncontested nomination if he chooses to run again.

But in the first weeks of what Laxalt calls "our quiet campaign of organization," the president's advisers are running scared. Despite their long-term optimism, they say Reagan is vulnerable on many issues, especially if the Democrats nominate the man the White House considers the strongest candidate, Sen. John Glenn (Ohio).

"I can't see where we can pull a 270 electoral vote coalition together today," said one adviser who fears Glenn most but thinks that Reagan would not be "home free" against Walter F. Mondale either. This Republican added that the Reagan vulnerability shows up more in analysis of the prospective electoral vote than in a trial heat matchups in the popular vote.

Among the populous states that Reagan swept in 1980 the president is now rated ahead only in California, Florida and, narrowly, in Illinois. New Jersey, Pennsylvania and even Texas are seen at this early distance as no better than tossups, and New York, Michigan and Ohio are considered probable Democratic states.

These are the estimates of several veteran Reagan regional political operatives and the president's cadre of political advisers. They include, in addition to Laxalt and Deaver, White House chief of staff James A. Baker III, California-based political consultant Stuart K. Spencer, Washington pollster Richard B. Wirthlin and White House political adviser Ed Rollins.

The prevailing view of this group is that continued economic recovery and Reagan's ability to keep attention focused on it is a key to political success.

"The engine that drives the successful reelect campaign has to be the economic engine," Wirthlin said. "Reagan was elected in 1980 because people saw a strong leader and, secondly, someone who would do something about inflation. And I think the over-arching theme that's going to structure the 1984 reelect is, 'Are we sufficiently along the road to justify extending this president another four years of incumbency'?"

Reagan's strategists also believe that he can use his communicative powers and his position as president to dominate public perception on a host of secondary but important issues such as education and the environment. Some of them suggest that the question of stability and continuity in office can be turned into a positive reelection issue.

"It would be good for America to reelect a president again after a series of one-term presidents," said Deaver, in a typical statement.

These evaluations of Reagan's potential strengths and weaknessess emerged last week from a series of interviews as the first organizational steps were taken in what promises to become a full-fledged second-term campaign.

It will be a campaign in which Reagan, as an incumbent, attempts to recapture the themes and constituencies that carried him to victory as a challenger in 1980. It is likely to be a campaign in which the man who is the chief executive officer of the federal government continues to rail against what he sees as the excesses and frivolities of government.

And it is also envisioned as a campaign in which a millionaire president with even wealthier friends tries to leave behind the limousines and the black-tie dinners, roll up his sleeves and identify once more with the blue-collar workers of Youngstown, Ohio, and Bridgeport, Conn.

Reagan is said to be impressed with the reelection campaign of his ally and friend, British Prime Minister Margaret Thatcher, who won by reemphasizing traditional conservative values. Like Thatcher, the president is expected to place renewed emphasis on the values of home, family and patriotism that have always helped him in the past.

The preliminary Reagan campaign organization contains no new faces. When a reelection committee is formed, Laxalt will serve as overall chairman, Rollins will be the nuts-and-bolts organizer, Spencer will return to his role as in-house strategist and Wirthlin, with help from longtime Republican pollster Robert Teeter, will provide the survey data.

Eventually, according to some officials, former transportation secretary Drew Lewis will be brought in as the operational campaign chairman if he is able to take a leave of absence from Warner Amex, the New York-based communications firm of which he is chief executive officer.

Reagan advisers say no final decision has been made on whether an "exploratory committee" will be formed soon after Labor Day or whether any committee will be activitated until Reagan formally announces, probably in late November.

Whatever the form, preliminary organizational work is proceeding with the knowledge and tacit approval of a president who still insists, in private as well as publicly, that he has not decided whether he will seek a second term. Though most Reagan advisers say he will run, Laxalt quipped, "It would be helpful if he would announce before the convention."

Those few advisers who still harbor doubts about Reagan's reelection intentions said that organizational needs require the assumption that the president is running again.

"We have to be ready to go when he does announce, and it's a tricky business getting the right people," one adviser said. "We have to keep some of the old Reaganites but we also have to broaden the base."

The absence of a Republican primary fight means that Reagan should be better rested than in 1980 and less likely to be damaged by the "age question," a veiled but significant issue which Reagan defused last time with jokes and vigorous campaigning. However, Reagan would be nearly 78 at the end of a second four-year term, and some of the inevitable frailties of age, particularly diminished hearing capability, have been evident in office.

"The problem is the same as it was before, maybe a little worse," one adviser said. "As long as he's healthy and looks good it's not a problem. But if Reagan stumbles through a performance, people say he's getting old. If a younger candidate has an off night, they say he's tired."

After 28 months in office Reagan appears to be in a far stronger position than Carter was at the same time, with a 46 percent approval rating in the Gallup Poll compared with Carter's 32 percent. However, Reagan's approval rating is lower than Richard M. Nixon's 50 percent and far lower than John F. Kennedy's 65 percent at the 28-month point of their presidencies.

Two other sets of statistics in the most recent Washington Post-ABC News poll illustrate strengths and weaknesses of the incumbent president.

Reagan's effectiveness as a communicator and the ability of a president to dominate the news agenda was demonstrated on the education issue, which he emphasized in a series of speeches including his weekly radio address yesterday.

The Post-ABC poll shows that the number of Americans who rate the schools highly, with an "A" or a "B" grade stands at 42 percent, almost unchanged from the response to an identical question in 1981. But Reagan has reversed the public perception of what his educational policies would accomplish.

In the 1981 poll 28 percent of those surveyed said that Reagan's policies would help education compared with 49 percent who said they would hurt. The latest poll is a reversal--46 percent say that Reagan policies would help and 29 percent say they would hurt.

Deaver maintains this is a demonstration of what can happen when a president emphasizes a position, in this case the view that educational standards should be higher, with which most Americans agree.

But another bit of data in the same Post-ABC poll shows the vulnerability of Reagan on the "fairness issue," the question of whether his policies benefit the rich more than they do the poor.

In response to a question about whether Reagan cares more about serving the poor, middle-income or upper-income persons or all equally, 58 percent answered "upper income" compared with 32 percent who said "all equally" and only 8 percent who said he cared most about the two lower-income categories.

The 58 percent figure is the highest ever recorded to this question in the Post-ABC survey, two points higher than it was in 1981 at the depth of the recession.

Reagan strategists generally agree that the fairness question represents a major problem, and some say it interacts with the "gender gap" issue because lower-income women were disproportionately affected by the recession. This also suggests that long-term economic improvement that benefits lower-income persons is particularly important for this president.

"If you're president, you get elected as president, not as a candidate," Teeter observed. "Reagan needs the recovery to continue, and he needs to stay out of trouble."

The crystal ball of the strategists is clouded by the situation in Central America, where the president's advisers believe in the wisdom of Reagan's policies while remaining dubious of their political impact.

"We're up in every other category," Deaver said. "On Central America, we're down in public perception and heading down."

It is an axiom of the presidency that taking unpopular positions that are necessary for national interests "go with the territory" of being in the Oval Office.

Nonetheless, many of Reagan's advisers would prefer to have more policy statements on Central America issuing from the State Department than from the president. They acknowledge that many Americans, of all persuasions, are fearful that U.S. involvement in the region could end up being "another Vietnam."

One Reagan adviser said last week that foreign policy issues are rarely determinative unless they are "war-and-peace issues." He also observed that events tend to dominate in foreign policy and that some issues, such as the seizure of American hostages in Iran, can cause Americans to rally around a president initially but wind up doing him irreparable long-term damage.

Few in the Reagan campaign are willing to guess whether Central America will become this kind of cuttting issue. But one adviser added, "You'd be safe in saying that nearly all of us would rather have the reelection campaign of 1984 fought on the issue of economic recovery than on the issue of aiding El Salvador."