After two months in office, the Reagan administration has started to lose definition and momentum. The early focus on economic recovery has been blurred by foreign policy issues that have them selves been further obscured by disputes over small points.

Gaps between the president's program and everybody's dream of licking inflation have also showed up. While Reagan can undoubtedly recoup his position, it is a question of how and at what price.

Those at least are the impressions I have on returning to the capital after three weeks abroad. During that period, attention shifted markedly from the president and his winning ways to Secretary of State Alexander Haig and his more forbidding mien.

The Haig strategy of putting the Soviet Union under pressures was well understood by the Russians, who do not insult all that easily. But it outran the capacity of the State Department to implement and articulate policy. Thus, to take one example, El Salvador was inflated into a big deal. Ghosts of Vietman stirred and under harsh questioning, the administration issued a series of conflicting statements that compounded confusion.

Apart from being slightly eclipsed, the president's economic policy showed internal difficulties. Inflation has been Public Enemy No. 1 for years now, the country has come to believe that the chief cause if government spending as symbolized by budget deficits. As long as Reagan identified himself as a foe of big government, he was in clover.

But the date for achieving a balanced budget has been officially postponed from 1983 to 1984. Estimates of coming deficits have been revised upward. Despite enormous emhasis on cuts in government spending, the two successive proposals advanced with high drama by the administration still fall some $30 billion short of the target set for 1984.

The race after a constantly receding deficit reminds many of Jimmy Carter's first days. Some in Washington see the possibility of self-immolation. More have begun to doubt there is any coherent relation between Reagan policies and the mastery of inflation. The country undoubtedly shares some of those doubts -- especially with regard to balancing the budget.

Striking evidence of the mood comes from the behavior of the Democrats. While Reagan was perceived to be St. George battling the dragon of inflation, they were relatively mute. Now that he looks a little more like Quixote, they are increasingly vocal in criticizing the social costs of his economic program.

The $140 billion tax cut projected by the administration for the next three years has come under heavy fire. The Democratic litany now includes a pointed reminder that under the administration formula, a family of four with taxable income of over $100,000 would increase its spending money by about 25 percent, as against a gain of about 5 percent for those with incomes under $15,000.

To the showing that the administration's tax program helps the rich, the Democrats are adding demonstrations that the projected spending cuts hurt the poor. One Democratic estimate figures that about 700,000 families, including 1.3 million children, will lose their public assistance benefits.

A letdown of sorts was bound to follow Reagan's brilliant debut. Certainly he can stem the tide. Still, the first 60 days demonstrate that he does not enjoy the background of crisis that made Roosevelt's 100 Days possible. To work his way, Reagan will have to make hard choices, and those choices are now being defined.

Congress will almost give the administration something less than the tax cut it seeks. Congress will also accept spending reductions that are serious, though not so drastic as those favored by the administration. At that point, the president-will have to make his choice.

He can veto, citing inflation and hoping to beat the Democrats in 1982 with the enthusiastic help of the Republican right. But he will run the risk of being charged with ideological intransigence and the inability to govern.

If he accepts the modified program, he will forgo his shot at the Democrats and any serious claim to have mastered inflation. He would have to settle for holding down rises in government spending -- which is something less than promised, but still no mean achievement.