"Winning Back America"? When was it lost?

Well, that was easy for any one of the 150 people in Room 2157 of the Rayburn Building to say last night. It all happened when Ronald Reagan took office.

"To me, because of a freakish political moment, a reactionary wing of a minority party has taken over the government," said Mark Green, explaining the title of his new paperback, "Winning Back America," the one with AMERICA spelled out in red and blue against a white cover.

"As the public sees that laissez isn't fair and Reaganism is Hooverism with a smile," Green said, "then Reagan's popularity will predictably plummet." Green, who worked for Ralph Nader for 10 years, is the founder and president of the Democracy Project, a liberal think tank.

The party was in honor of Green and the book. But the conversation was more a like slam-dunk session on the current administration.

"The Reagan election took America away from the working people and gave it to the oil companies, the rich folks," said Rep. Morris Udall (D-Ariz.), who stopped by right after Sen. Edward Kennedy (D-Mass.). Kennedy came with a copy of his new book, "Freeze," for Green.

Green, 37, talked with Kennedy briefly about the two books, which Bantam will promote together. Then Green walked around the room eating an apple, clutching the two paperbacks under one arm, greeting guests, friends and loyal liberals.

"I read the chapter on defense spending," said Joe Rauh, a founder of Americans for Democratic Action, "and Green's the first liberal with the guts to tell the truth about defense spending. Most liberals and most Democrats are squeamish about facing up to that problem."

Sen. Spark Matsunaga (D-Hawaii) also thought Green's book would be useful, but for slightly different reasons.

"I'm up for reelection, as you probably know, and this book may help," Matsunaga said. "Let the people know we're losing America."

He was standing next to Rep. Henry Waxman (D-Calif.).

"I think the failure of the Reagan administration to offer anything more than a trickle-down theory cloaked in supply-side rhetoric shows they don't have answers," Waxman said.

Then Sen. Gary Hart (D.-Colo.) arrived and talked a little about his friend Green. He opened by retelling the story in the preface of "Winning Back America" in which Ferdinand Foch, field marshal for the French during the battle of the Marne against the Germans in World War I, sent a dispatch to headquarters. His prospects seemed bleak. His center was giving way; his right had pulled back. It was time for an attack from the Left.

"Mark, regardless of the political forecast around him, has always been ready to attack," Hart said. "It's not an attack on people or personalities. It's an attack on ignorance. It's a positive attack. It lays out a program for the future at a time when the country needs hope and idealism."

And Green was not hesitant in his attack.

"The Reagan Revolution will last about as long as the Mets' dynasty after the 1969 series: one season."