The Republican Party is maintaining parity with the Democratic Party and could bring to an end two generations of an electorate with a strong Democratic tilt, according to a wide range of surveys, including polls taken for both parties.

"The data show that the days of Democratic dominance are over," said Peter Hart, who recently completed a major survey for the Democratic Party with two other pollsters, George Shipley of Texas and William Hamilton of Washington.

The findings of the Democratic poll coincide with recent surveys by The Washington Post and ABC News as well as those conducted by two Republican firms, Market Opinion Research (MOR) and Decision Making Information (DMI).

A Post-ABC poll of 1,506 people in June showed that 44 percent described themselves as Republicans and 47 percent as Democrats. An MOR poll with a similar sample size taken during the same period found that the two parties were in a dead heat, 48 to 48 percent.

On the basis of long-range examination of surveys, political scientists Thomas E. Cavanagh and James L. Sundquist concluded: "The data show exactly the pattern that would appear if a substantial realignment were in progress."

Cavanagh and Sundquist, who examined Gallup Poll results from 1940 to 1985 in a chapter of the recently published book, "The New Two-Party System," wrote:

"If the current trends persist into 1988, one would probably be justified in declaring that a realignment -- not one as decisive as that of the 1930s but one of a second order of magnitude -- has occurred."

Martin D. Franks, executive director of the Democratic Congressional Campaign Committee, acknowledged that "the Republicans are making progress on party identification." He disputed, however, Hart's conclusion that Democratic dominance has come to an end.

Franks argued that the GOP has become vulnerable on the issues of both Social Security and international trade. In addition, a number of Republican and Democratic strategists note that GOP gains are highly dependent on a continuing economic recovery. In the 1982 recession, support for the Republican Party took a nose dive.

At the same time, surveys and other analyses by politicians and academics are producing a number of potentially significant findings:

The voters who identify with the Republican Party are significantly younger than the general public, while the Democratic Party contains a disproportionately large share of voters 55 and older. In the most recent Post-ABC poll, for example, the GOP has a slight, 4-point advantage among those 18 to 30. This steadily declines as age increases, and among voters 61 and over, the Democrats have a 15-percentage-point advantage.

This pattern, which is in direct contrast to pre-1981 divisions within the electorate, reflects the strong belief among elderly voters that the GOP is more willing than the Democratic Party to cut Social Security, according to pollsters of both parties.

Younger voters are drawn to the GOP because of the economic recovery and the belief that President Reagan has restored the tradition of a strong presidency, they said.

Democratic pollster Hart and Republican Robert Teeter of MOR agree that the trends in voter allegiance will force each party to adopt new election strategies.

Republicans, according to Teeter, are moving away from being a homogeneous party dominated by middle-aged, white Protestants, to a more diverse core constituency that includes Roman Catholics, Hispanics and young people.

This will force the party to become more "coalitional," Teeter said. Candidates will have to use separate, targeted appeals to build support among GOP loyalists, just as it now does in general elections to draw in independent and Democratic voters.

Hart said the Democratic Party, no longer able to depend on a diverse majority coalition, will have to move in the opposite direction. The end of majority party status, "frees up the Democratic Party" to move away from coalition politics and to attempt to become a party "with a message."

Last year, Walter F. Mondale tried to unseat Reagan by attempting to restore the old Democratic coalition, and Hart was the chief pollster in that effort. Today, Hart says he welcomes the opportunity to let the Republican Party try its hand at coalition politics.

"It's a tough road," he said.

Teeter, however, contended that Republican voters will be united by a set of shared values -- support for a strong defense, domestic spending cuts and opposition to tax increases.

In addition, Teeter said his surveys suggest that much of the 59 percent of the vote that Reagan received last year provides a strong base for GOP candidates running for lower offices.

About 20 percent of those who backed Reagan voted for a Democratic member of the House, Teeter said. But in surveys, a majority of that 20 percent said they tended to prefer the Republican Party and wanted the GOP to control the House. Their congressional vote, they said, was influenced by their personal familiarity with the Democratic candidate.

If accurate, this finding suggests that a large bloc of voters are willing to shift to the GOP at the congressional level.

Detailed examination of the new voters brought into the electoral process in 1984 suggests that sharp racial and class divisions exist between newly registered Democrats and Republicans.

Cavanagh and Sundquist found that among new white voters, there was a striking "upscale and therefore conservative and Republican bias."

These new voters, Cavanagh said in an interview, are not the "white gas station attendants and young steelworkers," but a very affluent "yuppie contingent."

An unusually high 47 percent of the new white voters had graduated from college and 40 percent had incomes higher than the national median, even though three-quarters were under 30, according to Cavanagh.

In contrast, blacks, who made up a large proportion of new Democratic voters, differ with whites "not only on the substance of public policy, but on the most basic issue of all: the nature of the political agenda," Cavanagh said.

To support his argument, Cavanagh cited a poll by the Joint Center for Political Studies that showed a major white-black split over the role of government helping the poor, the importance of civil rights, inflation and the deficit.