The 1988 presidential election is likely to be a very close contest, with Democrats and Republicans both struggling to hold together shaky and internally conflicting coalitions, according to a massive voter survey released yesterday.

The special Gallup Poll of 4,224 individuals, about triple the size of the standard national survey, was commissioned and distributed by the Times Mirror Co., a communications firm that owns the Los Angeles Times and many other newspapers. It will be repeated periodically in the next year to monitor voter reactions to the 1988 campaign.

The base-line survey, based on personal interviews last spring that lasted more than an hour each, strongly suggests that the conventional view of American politics as a struggle between the parties or between liberals and conservatives is at least oversimplified and may be misleading.

"Our traditional view of the parties -- Republicans are free enterprise-oriented, affluent and conservative, while Democrats are peace-oriented, social reformers and liberals -- holds true for only one-third of the population," the study said.

The poll was headed by Andrew Kohut, president of the Gallup Organization, and Norman Ornstein, a political scientist on the staff of the American Enterprise Institute.

By examining interviewees' responses to a lengthy questionnaire, the authors identified 11 significant groups in the electorate. They were distinguished less by age, gender, race or economic status than by values dominating their thinking and lives.

Partisanship emerged as an important factor shaping their votes. But several other "value clusters" also proved particularly important.

Among them are degree of religious faith, tolerance or intolerance of other views, degree of belief in government's obligation to ensure social justice, intensity of anticommunism, belief or disbelief that the American system is responsive to the individual, confidence or lack of confidence in America achieving its goals, amount of economic pressure in the individual's life and basic confidence in or hostility toward business and government.

By comparing partisan identifications and voting behavior with these value dimensions, the authors defined 11 voting blocs whose main characteristics are outlined in the accompanying chart.

Looked at this way, the survey found that "in national politics, it is a virtual tossup between the Republicans and the Democrats."

Democrats have a larger core group, 41 percent to the Republicans' 30 percent. But when leaners are added and the difference in likely turnout rates factored in, "the result will probably be a 1988 presidential race that is very close," the study said.

The authors predict that "the winning coalition built by Ronald Reagan in 1980 and 1984 will be enormously difficult for the Republican nominee to hold in 1988" because it is composed of groups with very disparate values.

In 1984, Reagan drew virtually unanimous support from two groups of about equal size that now comprise the core of the Republican Party.

One group is the "enterprisers," an affluent, educated, white, suburban and largely male bloc, who are probusiness, antigovernment, antiwelfare spending but tolerant on social issues.

The other is the "moralists," less affluent, middle-aged, southern and white, strongly conservative on social and foreign policy, intolerant of dissent but in favor of social spending except for programs targeted to minorities.

The two coexist uneasily, the authors said, and one of the poll's surprises was that, at the time it was taken, Vice President Bush's lead over Sen. Robert J. Dole (R-Kan.) was found almost entirely among the "moralists," not "enterprisers," who might appear to be Bush's natural constituency.

Two other groups of even more contrasting character gave Reagan more than eight of every 10 votes, swelling his landslide. They are the "upbeats" and the "disaffecteds."

The "upbeats" are the under-40, middle-income whites, who have seen Reagan as the first "successful" president of their adult lives. They are not "yuppies" because few attended college, but they are optimistic about their lives and America's future.

The very different "disaffecteds" are middle-aged, alienated, skeptical of government and business. While the "upbeats" liked Reagan's "morning in America" themes, the "disaffecteds" responded to him mainly as an outsider challenging the system.

"The potential Republican majority built by Ronald Reagan is in four diverse parts and could easily crumble after his term," the study observed.

Democrats, however, may face even more serious problems in assembling a voting majority. The largest single group is the "New Dealers," an aging category with high percentages of blue-collar workers, union members and Roman Catholics. As they pass from the scene, the core of the Democratic coalition is weakened.

But it also is at odds with other constituencies. While the "New Dealers," like the others, favor social-program spending, they are conservative on abortion and public school prayer, relatively unconcerned about the environment, prodefense and anticommunist.

The " '60s Democrats," the coalition's next largest bloc, is in many respect the opposite: Group members are younger, predominantly female, upscale in education and income, strongly identify with the environmental movement, the peace movement and civil rights and are far more tolerant of diverse social behavior.

Three other groups contribute significantly to the Democratic vote. The "passive poor" and "partisan poor" both include large numbers of blacks and other economically pressured persons who look to the Democratic Party as the source of assistance. They are relatively conservative on social and foreign policy questions.

The final component is "the seculars," defined largely by the fact that members are not influenced by religious beliefs important to very large majorities of Americans.

Heavily concentrated on the East and West coasts, "seculars" want to cut military spending and oppose restrictions on abortion. Well-educated and well-informed, they could supply many more Democratic votes but are skeptical of candidates offered by the party in recent elections.

Many of the Democratic-inclined groups that had seen large-scale defections to Reagan returned to the party fold in the 1986 congressional elections, the study reported.

Democrats have important glue in their widely shared belief in using government to improve people's lives, and the foreign policy differences within the party are not likely to be brought "to a flash point" by any of the foreign policy issues on the horizon, the authors said.

But the party suffers among key groups of potential adherents for a perceived lack of governmental competence. Prosperity weakens its grip on other voters, and social issues are divisive, making reemergence of a dominant Democratic majority chancy at best.

The last two population groups essentially are political neuters because they do not appear in large numbers at the polls.

The "followers," who vote in only about one-half of their proportion to the electorate, are young, poorly educated and have a large percentage of blacks and Hispanics. One of every nine adults belongs to the "bystanders," who say they do not vote and have virtually no interest in government or politics. Mostly under 30 and white, many of them single, they are content to let others decide.

Rich Morin, director of polling for The Washington Post, called the new Gallup polling effort a "different and richer way of describing the political landscape. Models like this free us from the constraints of thinking about the electorate only in terms of party identification, sex, race, region, income or education."

Statistical techniques that Gallup used to develop its typology groups are not new, Morin said, nor is application of these techniques to political behavior.

"So-called 'psychographic,' as opposed to 'demographic,' analysis achieved something approaching fad status among market researchers and some political scientists a number of years ago," he said, adding that what is new is use of the tool to try "to help the general public understand an election as it is unfolding."