They made his day in the Senate yesterday, and at the White House later, it made the night.

After a resounding victory in the Senate on continued production of the MX missile, President Reagan relaxed for the evening, entertaining Argentine President Raul Alfonsin and his wife Maria at a black-tie state dinner. The guest list ranged from pro football star Doug Flutie to American Spectator editor R. Emmett Tyrrell Jr. to actress Gina Lollobrigida.

Out on the North Portico, where the Reagans greeted the Alfonsins, the president didn't hide his feelings. He pointed to his smiling face when reporters asked for a presidential response to the MX vote.

Comedian Mark Russell even picked up on the evening's mood. "When I came in, I had an open mind," he said. "By the end of dinner, I was ready for 10 MXs. By the time dessert came, I said, 'Star Wars all the way.' This place has no effect on me at all."

After dinner New Orleans jazz clarinetist Pete Fountain and his combo entertained the crowd, and moved Reagan to proclaim, "Tomorrow morning by executive order we're going to rename Pennsylvania Avenue Bourbon Street." And Nancy Reagan whispered in Fountain's ear. He said she told him that her late father " 'was watching tonight' -- he was one of my biggest fans."

It was Secretary of State George Shultz, though, who commanded an unexpected audience when he took Lollobrigida around the dance floor much as he had done with Ginger Rogers at another White House dinner. A prized photograph of the two of them hangs in his office and is inscribed by Rogers: "To George Shultz, for a minute I thought I was in Fred's arms."

Helena Shultz, who watched from the sidelines, said she suggested that Shultz ask Lollobrigida to dance.

"I said, 'Here's your chance,' " said Mrs. Shultz, who is recovering from recent surgery.

Lollobrigida said Shultz's dance steps surprised her. "He's very good. He said 'you must dance with me first,' so I obeyed," she said.

Guests chatted cheerfully with the president on everything ranging from California to golf. "California is a very hard place to leave after you've lived there," the president told one couple. "Southern California is not a place. It's a way of life."

Golfer Lee Trevino heartily shook Reagan's hand. "Thank you very much for the invitation," Trevino said. "Listen, when you get ready to take up the game, now . . ." he trailed off, but his wife Claudia added, "He's a great teacher."

The sparkle of the night was reflected in the dresses guests wore. Lots of beads and chiffon -- Lollobrigida in a silver and purple beaded dress cut low, with a diamond and ruby pin in her hair; Irene Cara, curvaceous in a gray dress etched with beads. Nancy Reagan wore a long black dress with a straight skirt and a long-sleeved top in a lacy pattern studded with black beads. Around her neck was a multistrand pearl choker. Maria Alfonsin wore a sleeveless teal chiffon dress. At least one woman decided to come dramatically different -- she wore a short white suit with a red bow tie.

New Jersey Generals quarterback Flutie was in awe. "Fantastic," he said of dinner. "I was fortunate enough to be sitting at the president's table."

They, of course, talked sports and about the president's football days and broadcasting days. "He told us some stories of how he got started. Tremendous." Flutie said he wasn't a registered Republican but noted, "I'm a Ronald Reagan fan."

And how does Flutie, who came with his fiance' Laurie Fortier, plan to spend all that money from his $8.3 million contract?

"Smartly, hopefully," Flutie said. "No big plans. We just bought a place in New Jersey. I'm hoping to get my feet settled."

He added later, "I came from a family that was always looking for where the next meal was coming from, and are we going to make it through to the next paycheck. It's nice to be able to do something nice for my parents."

In his remarks at the dinner, Reagan said he and Alfonsin first met last September at the U.N. General Assembly. The presidential campaign was in progress, and Reagan recalled, "I remember you remarked that although being president is a hard job, sometimes getting there is even harder."

And it reminded Reagan of another story. He described campaigning for the presidency in the 1976 primaries and how he went door to door in Texas introducing himself. One man of the house heard him out but was not impressed and wondered what his occupation had been before he became governor of California. Reagan said he had been an actor and as a clue said his initials were R.R.

The man yelled, " 'Ma, Ma, come out here quick. Roy Rogers is outside,' " the president said to laughter.

Although the president earlier had used the opportunity presented by Alfonsin's arrival to criticize the Sandinista government of Nicaragua, neither man mentioned Nicaragua last night.

But Alfonsin, in his response, did say that "in different aspects of international affairs, we have discovered many of our views converge. We also discovered a few differences in our analysis which should neither surprise or alarm us."

In his toast, Reagan lauded Argentina's "inspiring return to democracy." In fact, the president said, "the bond of democracy, the love of freedom" were some of the things the American and Argentine people have in common. Others are "the spirit of the frontier, exemplified by the gaucho and the cowboy."

Alfonsin apparently recognized his counterpart's interest in that frontier theme; he gave Reagan a leather gaucho belt with silver coins. For Mrs. Reagan from Mrs. Alfonsin there was a similar belt with her initials in gold on a mother-of-pearl inlaid silver buckle. Another gift among those Mrs. Reagan received was a red poncho made of vicun a, a fabric that hasn't been seen around the White House since the Sherman Adams days in the Eisenhower administration.

Among the guests were some noted cultural figures including Gregory Rabassa, the Queen's College professor and translator of Argentine literature, and Argentine filmmaker Maria Luisa Bemberg, whose film "Camila" appeared at a recent women's film festival here and has been nominated for an Academy Award.

In addition to Flutie, there were sporting types. Body builder and actor Arnold Schwarzenegger came with his mother, Aurelia, who was announced simply as "Mrs. Schwarzenegger."

"This is my mother," Schwarzenegger told the assembled reporters and photographers who snapped away. Schwarzenegger told his mother, "You have to be very friendly for the American press."

Tennis player Guillermo Vilas was making his first appearance at the White House. "It's the first time I am seeing my president, too," he said. "I haven't been in Argentina in two years. It's a thrill."

There also was Armand Hammer, chairman of Occidental Petroleum Corp., who yesterday announced that the government of Argentina had approved an agreement for a 15-year extension of Occidental's 25,000-barrel-per-day contract. "I believe this will encourage other companies to follow Oxy's example and participate in the opportunities for favorable investment in Argentina," Hammer said in a statement made available last night.

And there were other familiar faces, even if some of the names got a little garbled. "Miss Gina Lollollo -- ," stumbled the military aide.

"Lollobrigida," said the actress helpfully. She said she took pictures this morning as the dignitaries arrived. "The president, Mrs. Reagan, the president of Argentina," she said. The pictures were "all for my pleasure," she said.

Actress and singer Irene Cara (of the movie "Fame" fame) came with her fiance' Conrad Palmisano, the director of the film she just finished making. Asked if this was her first time at the White House, she thought for a moment and said, "The first time inside."

Russell made his usual dazzling entrance. "Right there," he said, pointing across the room to a portrait of a former president, "is Millard Fillmore, who is my patron saint."

Russell added, "I want you to know that I'm not here by computer mistake."

The comedian went to great pains to assure people that he had a legitimate reason for being invited. "Argentina is my life," he said. "I'm just so afraid I'm going to say, 'Good evening, Mrs. Peron.' "

The guests dined on smoked salmon, crown of veal medallions with basil sauce and spinach timbale of gruyere souffle', capped by raspberry baskets with sabayon sauce and three California wines.

And for the record books: This was the first state dinner at which a president was attended by a female military duty aide. The honor went to 33-year-old Coast Guard Lt. Cmdr. Vivien Crea. She preceded the president and Mrs. Reagan and their guests down the Grand Staircase as the presidential party entered for dinner.

Guests at last night's White House dinner:

President and Nancy Reagan

Raul Alfonsin, president of Argentina, and Maria Lorenza Barreneche de Alfonsin

Edison Otero, president pro tempore of the Senate

Juan Carlos Pugliese, president of the Chamber of Deputies

Dante Caputo, minister of foreign relations and worship, and Anne Caputo

Lucio Garcia del Solar, ambassador to the United States

Juan V. Sourrouille, minister of economy

Jose Ignacio Lopez, presidential spokesman

Col. Juan Manuel Tito, chief, military house of the presidency

Carlos Lacerca, secretary of industry

Lucio Reca, secretary of agriculture and livestock

Enrique Quintana, director of protocol

Raul Francisco Maria Alconada Sempe, undersecretary for Latin American affairs

William Althaus, mayor of York, Pa., and president, National Conference of Republican Mayors, and Karin Althaus

John B. Armstrong and Henrietta Armstrong, King Ranch, Texas

Sergio Arredondo and Alma Arredondo, Pasadena, Calif.,

Clarence M. Bacon, national commander, American Legion, and Helen Bacon

Ralph Baruch, CEO, Viacom, and Jean Baruch

Maria Luisa Bemberg, Argentine film director

Sen. Lloyd M. Bentsen (D-Tex.) and (B.A.) Bentsen

Vice President and Barbara Bush

Irene Cara, actress and singer, and Conrad Palmisano

Leo Cherne, economist and Medal of Freedom winner, and Phyllis Cherne

Thomas L. Clancy Jr., author, and Wanda Clancy

Edward Conesa, Harvard University

Legree Daniels, chairwoman, National Black Republican Council, and Oscar Daniels

Michael K. Deaver, White House deputy chief of staff, and Carolyn Deaver

William H. Draper III, president, Export-Import Bank of the United States, and Phyllis Draper

George and Anne Embrey, Columbus, Ohio

Hubert Faure, New York

John Ferrugia, CBS, and Mona Ferrugia

Amalia Lacroz de Fortabat

Pete Fountain, clarinetist, and Beverly Fountain

Doug Flutie, New Jersey Generals quarterback, and Laurie Fortier

Ted Graber, interior designer

Meg Greenfield, editorial page editor, The Washington Post

Nina Griscom, New York

Armand Hammer, chairman, Occidental Petroleum Corp., and Frances Hammer

Darah Harrell, daughter of Pete Fountain, and Benjamin J. Harrell

Sen. Chic Hecht (R-Nev.) and Gail Hecht

Enrique Anderson Imbert, Harvard University, Department of Ibero-American literature, and Margod Imbert

David Lloyd Kreeger, president, board of directors, Corcoran Gallery, and Carmen Kreeger

State Sen. Cyndi Taylor (Tex.) and Joseph Krier

Jewel LaFontant, attorney and former deputy solicitor general

Archbishop Pio Laghi, pro-nuncio of the Holy See

Rep. Jerry Lewis (R-Calif.)

Gina Lollobrigida, actress, and Dr. Allan Lazare

Caroline Hudson Lynch, New York

Paul Maginot and Colleen Maginot, Templeton, Calif.

Dr. Thomas F. Magovern and Bruni Magovern

Robert McFarlane, national security adviser, and Jonda McFarlane

Langhorne A. Motley, assistant secretary of state for Inter-American Affairs, and Judy Motley.

Frank V. Ortiz Jr., U.S. ambassador to Argentina, and Dolores Ortiz

Cesar Pelli, chairman, Department of Agriculture, Yale University, and Diana Balmori

Donald Petersen, chairman, Ford Motor Co., and Jody Petersen

Robert Potash, author on Argentine history, and Jeanne Potash

Maria Prats, daughter of President Alfonsin, and Dr. Eduardo Prats

Jorge Preloran, University of California, Department of Theater Arts, and Haydee Preloran

Gregory Rabassa, Queen's College, department of Romance languages, and Clementine Rabassa, translator of Argentine literature

Donald T. Regan, chief of staff to the president, and Ann Regan

Michael Hill Robinson, director, National Zoo, and Barbara Robinson

Selwa Roosevelt, chief of protocol, and Archibald B. Roosevelt Jr.

Mark Russell, comedian, and Alison Russell

Barry Sanders and Nancy Sanders, Washington, D.C.

John T. Sargent Sr., chairman, Doubleday and Co., and Elizabeth Nichols Kelly

Arnold Schwarzenegger, actor and body builder, and Aurelia Schwarzenegger

George Shultz, secretary of state, and Helena Shultz

Sen. Arlen Specter (R-Pa.) and Joan Specter

Harry Stone, senior vice president, Motion Picture Association of America, and Lucia Stone

Clarence Thomas, chairman, Equal Employment Opportunity Commission, and Lillian McEwen

Lee Trevino, golf pro, and Claudia Trevino

R. Emmett Tyrrell, editor in chief, American Spectator magazine, and Judy Tyrrell

Guillermo Vilas, tennis pro

Mr. and Mrs. Peter W. Webb.