Shades of autumn, shadows of war darken America's capital

The mood in Washington is doubt, uncertainty, and apprehension as America tries to puzzle out President Reagan's exposition of events in the Caribbean and Lebanon. The atmosphere here is almost one of a nation at war.

During past crises, clusters of sightseers have gathered in front of the White House, peering through the tall iron rails. Now, another group has arrived predictably.

Across the street in Lafayette Park, the yellow beds of chrysanthemums are fading in the crisp fall weather.

The mail slots in the press galleries' bulletin boards, filled with congressional handouts commenting on events of the day, fairly explode with leaflets on Grenada.

White House spokesman Larry Speakes stands in a jammed briefing room and endures a two-hour press conference with smoldering reporters who feel they were told Sunday night that there would be no invasion - only to find that it was under way.

Meanwhile, America and world leaders are coming to some sort of consensus on what is happening, with one of the most significant comments coming from British Prime Minister Margaret Thatcher. She reportedly telephoned Mr. Reagan Monday night in an effort to stop the Caribbean invasion, but she has refused to condemn the action.

Can Reagan persuade the public that his course has been wise, and that he can insert and extricate US expeditionary marines smoothly in the Caribbean? The moment of truth seems to be approaching.

Meanwhile, the global drama plays outside. From Moscow comes a new arms offer. In Beirut, marines move to safer quarters. The United States is criticized in the United Nations for its invasion of Grenada.

And here in Washington the inevitable political reexamination begins. What will Democratic House Speaker Thomas P. O'Neill Jr. (D) of Massachusetts say? He has become a symbolic leader, giving the signals: Support the President in a war crisis now; later will come questions, debate, and perhaps confusion. Has Reagan acted wisely? Has he adequately consulted Congress under the 10-year-old war powers resolution?

Preliminary evidence piles up before President Reagan speaks. He is already being criticized. There is the federal budget deficit, approaching $200 billion. There is the question whether US marines were adequately protected in Lebanon. There is the usual disagreement during a president's third year over the administration's success. Over breakfast, House GOP leader Robert H. Michel of Illinois tells a group he is certain Reagan will have ''broad public support.'' He says he accepts the global position in the Caribbean: ''We are going to get the Cubans out of there; we are going to get the Russians out.''

But former Undersecretary of State George W. Ball argues that the US role in Lebanon as ''peacemaker . . . interposed between fanatical warring factions is clearly not an appropriate undertaking.''

Across Pennsylvania Avenue from the stately White House, another band of activists arrives. There is a place for them with their loudspeakers, and the police politely guide them to it. Lafayette Park's five built-in chess boards on cement stands, normally crowded by zealots, are empty in cold weather. Time now for another kind of chess.