Well, you have to admit he's damned if he does and damned if he doesn't, but President Ronald Reagan got through the centennial of Franklin Roosevelt's birth with a maximum of grace yesterday.

A thinly veiled pout by Franklin Roosevelt Jr., a few days before, seemed to criticize Reagan for cashing in on the Roosevelt memory -- there Reagan would be (he said) with what's left of the Roosevelt family. As if Reagan were on intimate terms with them.

These things always delight the folk of Washington. The idea of making a lot of hay by being seen with Franklin Roosevelt Jr. was delightful to many who mulled over it a bit.

If, on the other hand, Reagan had ignored the centennial of President Roosevelt's birth, people would have emerged from every crack in the woodwork with trumpets of ire. How dare he not even acknowledge the centennial of a great president?

So either way, Reagan stood to be criticized. Not that it seemed to bother him much. His face was even pinker than usual, his smile even more dazzling, and his awareness that most people find him a jolly good fellow, even more profound.

In the morning he went to a Roosevelt exhibition at the Museum of American History.

"Dear," said Mrs. Reagan, in a voice she trusted was not too loud (she was 50 feet from the president) but which she hoped would carry.

She meant what wives commonly do when they say the word: Come on, laddy, let's go.

Few incumbent presidents attend museum showings, and the honor of it all was not lost on Roger Kennedy, the museum's director.

"He was at his nicest. The emphasis was not on a Democratic president, of course, but on the people of America. I think the nature of the show came as a nice surprise to him; it is not, after all, a political show. The president's mood at the end was rather gentle and soft. He and Mrs. Reagan listened to a tape of Eleanor Roosevelt that is played, and they smiled.

"When he heard the voice of Will Rogers, the president beamed and said, 'Oh. Will.' I imagine they knew each other."

The Reagans admired an old General Electric refrigerator, and all the baggage of common life in the 1930s.

"Mrs. Reagan made a real effort to speak to the guys who work behind the scenes to get shows like this properly installed. And of course the president's visit was a real effort. It was not like a Republican president coming to view a show about a Democratic president," the director said. "He was an individual who remembered much of those days. He looked down the maw of an old movie camera -- of course he remembers all that.

"He said when he left that he was going out of here dripping with nostalgia. The president and his wife admired everything, the chicken in the pot, and they were very moved."

Later the president was host at a White House lunch attended by many of the Roosevelt family (Jimmy Roosevelt sat at the president's own small table, which was set with Roosevelt administration china, though the other guests at other tables only got Lyndon Johnson china) and people who remembered Roosevelt well. Among them were Grace Tully, Roosevelt's old secretary, and the White House maitre d'hotel, John Ficklin, who dates from the Roosevelt era.

The president rose to deliver a toast at 2:30 p.m., by which time even the heaviest eaters had pretty well polished off the chicken breasts Veronique, saying that the lives of everybody there had been intertwined with that of Roosevelt. Which was partially true in the sense that the New Deal affected all who have lived in America since.

In a nice gesture, the president quoted old Sen. Jennings Randolph (D-W.Va.) that the thing about Roosevelt was this: He made everybody feel that "I count."

In a pretty salute to press philosophers and wits, the president quoted the late Walter Lippmann, who was always on target, in one of that writer's profound insights, that Roosevelt was a perfectly nice fellow with no qualifications to speak of, who wanted to be president.

"I think I have been hearing an echo," Reagan said. (Laughter.)

Reagan said he first saw Roosevelt in Des Moines in 1936, riding in an open-top car.

"What a wave of affection and enthusiasm ran through the crowd," he said, and he tossed out several additional salutes. Roosevelt "drawing from us confidence and enthusiasm," inspired Reagan and millions of others "with new hope."

As a matter of fact, he went on, Americans always sense "when things have gone too far -- when it is time for fundamental change."

This, needless to say, would not be utterly endorsed by everybody hearing him. But the president did not go very far down the line that he was Roosevelt's true heir, and settled for observing that Roosevelt was "a great man who led the nation" in times of etc.

"Happy days," said the president, raising his glass, as the room rose to its feet, with what was left of their Chardonnay, "now, again, and always."

Everybody gulped a swig and clapped, as the red-coated Marine musicians out in the entrance lobby started up the old tune.

President Reagan smiled joyously, marched down the main hall by the old state reception rooms, turned into the lobby himself, nodded to a stray reporter who had taken a shortcut out of the East Room -- thank God, you can't tell a reporter just by looking -- followed by Sen. Edward Kennedy (D-Mass.), who was gnawing on a cigar, Speaker Tip O'Neill, David Ginsburg, and a fitful flood of folk, some quite old and some still hearty, down the stairs to the basement.

Whither the press were forbidden to follow. Who can say what went on in the basement. Still, the president had got pretty admirably through a day that not every Republican successor of President Roosevelt would have relished.