When the lights in the House chamber had dimmed, and the notables had been escorted off the scene, two congressmen, one Republican and one Democrat, found themselves in an elevator.

The Democrat asked the Republican, "What did you think of the speech?"

The Republican hesitated for a minute and then he said, "Yes," and laughed.

It was a hard speech to review.

The State of the Union offers the chance for a kind of dialogue between the president and Congress. The members can vote only with their hands, but they do manage to get something going.

When the president entered, the Republicans issued a kind of get-well card with their applause.

They beat their palms sore, as if to tell him that, no matter what the doctors say, he is "on the mend," which is how he wanly described the country's condition.

The Democrats had nothing to say about most of the speech.

But in their councils of war they had studied every line to see where they might get in a word, so to speak. They found their opportunity on the next to the last page of the text. The word was passed to the troops.

When Reagan said, "We who are in government must take the lead in restoring the economy," the Democrats went into action, bringing a touch of street politics to the affair.

Thunderous applause broke out in their ranks.

Young Edward J. Markey of Massachusetts leapt to his feet. Others quickly followed, until the whole Democratic side of the chamber was up, clapping madly at the sound of words they had waited two years to hear.

They also gave the unhorsed supply-side cowboy his one opportunity of the evening to show that he has not lost all his flair--and fight.

He knew the rising ovation was a razz, and he came back smartly.

"I thought you were all reading the paper," he said. The Republicans, proud to see a flash of his old form, got up and gave an answering salvo.

It was the one real exchange of the evening.

The reason that the Republican congressman could find no words for the speech from his leader is that it was not so much a declaration as it was a battle report.

Reagan is being fought over like the children in a divorce case.

Two groups are seeking custody. On one side is the "Let Reagan be Reagan" faction, whose most vociferous spokesman is James G. Watt, the secretary of the interior, who paused in his pummeling of Indians and environmentalists to speak the fighting words, "Let Reagan be Reagan."

They are the true believers who love the revolutionary Reagan who said two years ago in the same spot that government was the problem, not the answer.

Arrayed against them are the forces of change, staffed largely by moderate Republican senators whose leader, Howard H. Baker Jr. of Tennessee, announced that he is quitting the struggle for Reagan's soul. They are the advocates of unlovely reality. They counsel another course, especially if Reagan is to run again.

Apparently, each side was given equal time.

No flags waved, no bugles sounded in what appeared to be a joint communique from the front.

The drafters obviously were under instructions to make the report as drab as possible. They succeeded most notably in the opening lines, which were of a banality worthy of a country-club treasurer's annual report. Reagan noted that it was the 196th time that a president had given a State of the Union. "That's a lot of reports," he observed flatly.

The new Reagan called for a "freeze" in domestic programs.

The old Reagan hung on to the military budget, which he insisted is not the cause of the deficits he once promised to eliminate, although he did promise $55 billion in defense savings in the next five years.

The new Reagan wants government money for extended unemployment benefits and for retraining the jobless. But the old Reagan still is fighting fraud in government programs, citing $1.1 billion in abuses in the food stamp program.

There was a trigger tax, and for old times a plea for a school prayer amendment.

The old crowd carried the day on arms control.

Now that everyone in Europe, including Franz Josef Strauss, the German equivalent of Sen. John G. Tower (R-Tex.), has come out against the "zero option," Reagan is sticking with it. An arms agreement depends on Soviet good behavior.

The State of the Union accurately reflected, to the satisfaction or dismay of the partisans in his immediate audience, the divisions in Reagan's mind, his staff and his party.

Beyond that, it only reinforced the widespread opinion in the city that for the next two years, two of his most critical listeners, House Speaker Thomas P. (Tip) O'Neill Jr. and Senate Majority Leader Baker, will be running the country.