Washington — Republicans have a dream: not only reelecting President Reagan in November but seeing the GOP become the majority party in the country. Could it happen?
As important as who wins on Nov. 6 will be what the election says about the patterns and trends in party affiliation. There are signs that the Republicans, while still the minority party, are beginning to gain on the Democrats. This is far from anything that can be called a historic realignment of party constituencies, but it is a phenomenon that is catching the eye of political experts.
The gains are seen in significant areas:
* Young people under the age of 25 are showing strong support for Mr. Reagan and the GOP, a shift attributed in large measure to a preoccupation with jobs and conservative attitudes on the economy.T
* Many ethnic Americans, especially Roman Catholics, are moving into the Republican ranks, largely because they are now in the more affluent middle class but also because many of them hold conservative social views.
According to a new survey by GOP pollster Robert Teeter, the number of Americans now identifying with the Republican Party is almost equal to those identifying with the Democrats. Out of 1,200 people polled in mid-September, 45 percent said they identified most closely with the Republicans and 46 percent with the Democrats. Four years ago, the comparable figures were 40 percent for the GOP and 53 percent for the Democrats. (These figures include independents who say they lean toward one party or the other.) Equally significant are appreciable gains in the number of registered Republicans in the Deep South, where the party still trails the Democrats but has moved up, and in the East and North Central regions, where the GOP is now ahead by 7 points.
''We are seeing an increase in party identification which, (1) indicates how people will vote and (2) translates beyond party identification to approval for Republican policies,'' says Linda DiVall, an official with the Republican Congressional Campaign Committee, which commissioned the Teeter study.
The Gallup poll is finding similar results.
''We see the Republicans drawing increasingly closer in the last three surveys, taken over the last month,'' Andrew Kohut, president of Gallup, said in an interview. ''We've never seen it this close.''
He would not disclose the specifics of his latest poll. But a Gallup survey in August showed that the number of voters calling themselves Republicans rose by 4 percentage points to 28 percent, compared with 1980. The number identifying themselves as Democrats dropped by 4 percentage points, to 42 percent.
Polls are imperfect measurements, and experts are quick to caution that it is too early to interpret the figures as signs of a strong burgeoning party realignment.
''Party affiliation is a state of mind,'' says Mr. Kohut. ''It has an ebb and flow, pops around, and it's hard to distinguish between party affiliation and choice of candidates. There are serious changes going on, but it's too early to say whether this is a true realignment or simply reflects the Reagan lead and the fact that Republicanism is more popular right now.''
''The test will be the state legislatures and city councils,'' says Curtis Gans of the Committee for the Study of the American Electorate. ''This will tell you whether the affiliation is presidential - as between Reagan and (Walter) Mondale - and therefore likely to be temporary, or whether it is playing out at the lower level and therefore lasting.''
''I don't think it's lasting,'' adds Mr. Gans, ''because on issues the public is more Democratically oriented.''
Republican Party chairman Frank Fahrenkopf says the GOP has registered 2.7 million new Republicans, many of them young people, and he says he expects to reach 3 million by the time most state registration windows close in a little over a week. Democrats also claim millions of new voters, but Mr. Fahrenkopf says he believes their lists are not as well pinpointed for purposes of getting out the vote.
Most specialists tend to believe that the improving economy and approval of Reagan's leadership account for the rise in the GOP's popularity.
''This election is very much a test of Reagan, not just of him personally, but of his being in control of a country that is in better shape,'' says Kohut.
Social and religious issues may also be a contributing factor. Political scientist A. James Reichley, of the Brookings Institution, documents a swing of major religious groups into the GOP camp in recent elections, in part because of the party's increased emphasis on conservative moral values.
Thus, substantial majorities of mainline Protestants voted for Reagan in 1980 , he notes. Roman Catholic voters favored Reagan over President Carter by 7 points. Evangelical Protestants, previously passive as voters, also voted heavily for Reagan.
Dr. Reichley acknowledges that pocketbook issues and foreign policy concerns are the dominant factors in deciding elections. But he adds that religion has the potential to affect 10 percent of the vote and maintain party loyalties despite any economic reverses.
The ''religious factor, operating differently among different faiths and denominations, is the one element now visible in American politics that could tip the scales to an enduring realignment,'' he writes. ''If culturally conservative Catholics, Jews, and evangelical Protestants begin voting for Republicans for Congress and state and local offices, as well as for president, and most mainline Protestants maintain their loyalty to the Republicans, a major realignment will be under way.''
At the moment, says Reichley, of the nation's five major religious groups, only black Protestants are now firmly in the Democratic Party. And Reagan and the conservatives are making a concerted effort to bring most major religious groups into the Republican Party - an effort that has the Democrats scurrying to stress traditional moral values and to warn of the danger of an erosion of church-state separation.
GOP leaders are cautious in forecasting an enduring change in party affiliation. ''We may be seeing the birth of a realignment,'' says Fahrenkopf. ''The next two election cycles will be the determinant.''
In Fahrenkopf's analysis, there are three reasons for the movement into the Republican Party. One is the widespread perception of Reagan as a strong leader in contrast with Walter Mondale. Second, in addition to their concern about jobs in the future, young people under 25, have known only two presidencies - the Carter administration with its economic ''mess'' and the Reagan presidency with its improved economic climate.
Last, there is the intangible factor of ''pride and patriotism.'' Under Reagan, says Fahrenkopf, there is ''a feeling of being proud of being American again'' and of ''extreme patriotism.'' This, he says, contrasts with the ''malaise'' felt by the public during the Carter period.