Washington — This week begins the election-year countdown for the Reagan presidency. With his State of the Union speech to Congress on Wednesday, followed by presentation of the fiscal 1985 budget and economic report next week, the President will set the stage and sound the themes for the 1984 Republican election campaign. When he formally announces on Sunday that he will seek a second term - assuming he does - the political battle will be joined.
There is no doubt about Mr. Reagan's basic message. From the powerful podium of his office, the President already is trumpeting what he considers to be the achievements of his administration: a resurgent economy at home and a more assertive America abroad. In contrast to three years ago, when he assumed the presidency, Reagan says confidently, things are better and the nation is launched on a new course.
At the same time, with his political antennas attuned to Democratic critics and to an ambivalent public mood, the President is beginning to outline the chores of a second term.
''We still have much to do - wringing out more waste and fraud in government, putting more Americans back to work, attacking the federal deficit, getting inflation and interest rates down still further - these and other great labors lie before us,'' he told a gathering of political appointees last week.
As he seeks to control the political debate in the weeks and months ahead, say GOP strategists, the President will have to respond to concerns on both the economic and foreign policy fronts.
The latest economic figures, for instance, suggest that the President has something to shout about but cannot be entirely free of worry about the future. On the positive side, inflation rose by only 4.3 percent in 1983, according to the Commerce Department. Also, the economy as measured from the fourth quarter of 1982, the beginning of the recovery, through the same period of 1983 grew a strong 6.1 percent - about the same as in previous recoveries. Personal consumption and investment in new plant and equipment also rose at healthy rates. Personal disposable income was up 3.2 percent in 1983.
However, uncertainty about the coming months continues. The economy in the fourth quarter of 1983 slowed to a moderate 4.5 percent annual growth rate, a slowdown that is normal in a maturing economic recovery. But, while the administration expects the economy to maintain a real growth rate of 4.5 percent in 1984, some economists say it will slow even more. One reason is the nation's worrisome trade deficit, expected to reach $90 billion this year. Because of the high value of the dollar, export sales of American goods continue to decline sharply and American imports of both consumer and investment goods are growing.
''Our exporters have been hurt by the strong dollar, weak foreign economies, and financial problems of developing countries,'' Commerce Secretary Malcolm Baldrige said last week. ''American companies are also facing stiff competition in domestic markets.'' The situation will get worse before getting better, he added, and the country is in for some ''rough months.''
Others, too, warn that, if not checked, this trend will continue to act as a drag on the United States economy. Jerry J. Jasinowski, chief economist of the National Association of Manufacturers, says if the American economy continues to lag in the trade area, economic growth in 1984 could be cut by as much as 1 percent.
This is why Reagan and his aides now talk of the importance of attacking the ballooning budget deficit and reducing high interest rates. Still, whatever the importunings of Reagan's economic adviser, Martin S. Feldstein, to do something this year, the administration remains firm against any action in 1984 because of the political constraints in an election year. It insists it will seek to reduce the deficits through spending cuts, not tax increases - which Reagan maintains would hurt the economy more than the deficits - and it blames Congress for the deficit problem.
In political terms, however, the President appears to confront more of a challenge on the diplomatic than the economic front. Foreign policy looms as a potential vulnerability in November.
A new Washington Post/ABC poll shows a decline in public support for Reagan's policies, especially in the Middle East and Central America. According to the poll, 50 percent of Americans now give the President a negative rating for his handling of foreign affairs. About 60 percent think the US does not have clear goals for the US Marines in Lebanon, 58 percent would like to see the troops removed, and 60 percent say the US is trying to do too much with its military overseas. At the same time, those polled were equally divided on whether the US today is more secure internationally than when Reagan took office.
As he prepares for the election year, the President will try to persuade Americans that the US position has improved over three years ago, when the the nation's defenses had ''grown weak,'' US influence was ''shrinking,'' and the Soviets were throwing their weight around. Citing his foreign policy moves, the President says that the invasion of Grenada ''set a nation free,'' there has been progress in Lebanon, however slow, and the US is now strong enough to negotiate an arms reduction agreement with the Russians.
While critics take issue with such assertions, there is a feeling here that public opinion at home and abroad is forcing Reagan to seek better relations with the Soviet Union.
And, while the recent meeting between Secretary of State George P. Shultz and Soviet Foreign Minister Andrei Gromyko in Stockholm did not produce any concrete results, it is viewed as having opened the door to an improvement in the months ahead. The enhanced prospects for renewal of the East-West talks on mutual and balanced conventional force reductions in Europe and the further easing of US sanctions on Poland are positive straws in the wind, say foreign policy experts.
The President, at any rate, continues to hold out hope for an arms control agreement and progress in the international arena.