STATE OF THE UNION; Setting the agenda for Election '84

President Reagan's campaign wooing has begun. He ostensibly addressed Congress in his State of the Union speech Wednesday night. But in the televised message, suffused with optimism, patriotic fervor, and sentimentality, the President once again reached over the heads of his immediate listeners to the broad electorate beyond.

Demonstrating his sensitive political antennas, Mr. Reagan presented an agenda targeted on various constituencies across the nation. For the conservatives he promised to strengthen ''traditional values.'' For the environmentalists, he offered more federal money. For the unemployed, he said that they must not be forgotten.

For the American people at large, he stressed peace and a resurgent economy. ''America is back - standing tall, looking to the '80s with courage, confidence, and hope,'' he declared in a phrase expected to set the dominant theme of the election campaign.

With equal political flair, Reagan brought Congress into the act in areas where he faces the greatest vulnerability: the budget deficit and foreign policy. He called for a bipartisan effort to work on reducing the deficit, thus deflecting from the White House sole blame for this economically dangerous condition. Similarly, he thanked Congress for its cooperation on foreign policy issues, thereby seeking to make still-unresolved diplomatic problems a shared responsibility.

Political observers here agree that oratorically and politically it was a masterly performance that probably appealed to large segments of his television audience. This year's State of the Union message was in fact delivered against the background of a high approval rating for the President in the polls. A recent New York Times/CBS News poll showed the President holding a lead over the Democratic front-runner, Walter F. Mondale - a lead attributable largely to the strengthening economy.

Political experts, however, say the President's speech skillfully concealed many problems and contained some contradictions. On the budget deficit, for instance, Reagan drew the biggest applause when he declared, ''We must bring federal deficits down.'' But while this conveyed a sense of bipartisan agreement on the goal, there is fundamental disagreement over how to accomplish this.

Reagan called for a bipartisan panel to negotiate a three-year, $100 billion deficit-reduction plan. He also proposed a study of ways to simplify the nation's tax system and a constitutional amendment that would enable the President to veto specific portions of spending bills.

But it is unlikely the latter will be adopted. And the tax-simplification study will not be completed until December, after the election - mention of which sparked a burst of ironic laughter. As for the three-year deficit-reduction plan, which the President calls a down payment, this could produce a modicum of progress inasmuch as the Democrats would not want to be seen stonewalling a bona fide effort to reduce the deficit.

But even if the negotiation is successful, this would do little to close an annual budget gap of almost $200 billion. Mr. Reagan made no mention of making cuts in defense spending or tackling social security and other entitlements - the only areas where substantial cuts are possible. At the same time he proposed a major new space program - a permanently manned space station to be built within a decade - that will also add to government spending. The nation, in other words, will likely live with the deficit for some time to come.

The President also gingerly skirted the hard realities of his earlier pledge to reduce the size of government. He noted that he had cut the rate of growth in federal spending and pointed to some budget savings. But he did not mention the politically sensitive fact that government accounts for a larger share of the nation's gross national product now - 25 percent - than when he took office.

On the environment, the President promised a large budget increase for the Environmental Protection Agency and initiatives to reduce the threat of hazardous wastes and restore Chesapeake Bay. But on one key concern of environmentalists, acid rain, he offered only to double research on the problem, not to push specific actions.

Political observers are also intrigued with the President's focus on traditional values. In the past three years, Reagan has not vigorously pushed his social agenda, including anti-abortion legislation, tuition-tax credits for private schools, and prayer in the schools. But, judging from his State of the Union message, he intends to give these themes higher priority if he runs for and wins a second term.

By reaffirming his support for anti-abortion laws and tuition-tax credits for parochial and other private schools, Reagan is appealing to blue-collar and ethnic voters, political analysts say. He is also covering his flank on the right: Conservatives have been unhappy with the tepid White House efforts in this area.

But on some social issues Reagan is running against the popular grain. The vast majority of Americans, for instance, support giving women the right of choice on abortion. Many Americans also oppose tax concessions for parents who send their children to independent schools. These and other controversial questions, such as prayer in the schools, have also run into judicial roadblocks.

Significantly, the State of the Union message devoted the least attention to foreign policy. This is the area where polls show public concern growing and the President's ratings slipping.

Clearly addressing the edgy public mood and hoping to defuse the issue for the Democrats, Reagan again - as he has done in recent days - muted his rhetoric about the Soviet Union and reaffirmed US willingness to build peaceful relations with Moscow and achieve ''real and equitable reductions'' in nuclear arms.

Without dealing at length with Lebanon, the issue that most concerns Americans now, according to polls, the President nonetheless insisted on keeping the US Marines in Lebanon, saying they were helping to ''break the cycle of despair'' there. ''We must not be driven from our objectives for peace by state-sponsored terrorism,'' he stated.

On balance, Reagan avoided specifics, stressed broad themes, and sought to set a tone of confident, buoyant presidential leadership, of a country rebounding from economic and spiritual gloom, and of a vigorous, promising future for the nation. Whatever the gaps or contradictions in his positions, say political experts, the President effectively addresses the American people's need for hope.

''He's got an awareness that Americans need to believe in something,'' one analyst says. ''It's all associated with the idea of the American dream. He understands this and builds on it. And with the economy going well he is able to do this.''