America's new ambassador to Switzerland doesn't know if he was ever Ronald Reagan's role model, but he, too, once had Shirley Temple as a leading lady (he was "daddy" to her "Little Colonel"). And he, too, used acting as a springboard to enter politics.

"I became a governor before he Reagan did, ha, ha," said John Davis Lodge, one of those Lodges and elected governor of Connecticut in 1950, at a party last night after his swearing-in at the State Department by Chief Justice Warren Burger.

Lodge, who will be 80 in October, entered politics in 1947, after World War II, when he was elected to Clare Boothe Luce's congressional seat from Connecticut. Between 1932 and 1941, though, he appeared in a couple of dozen films, and in "The Scarlet Empress," he had a particularly memorable role opposite Marlene Dietrich.

Asked what she was like to kiss, Lodge said it was a question that his older brother, Henry Cabot Lodge, also asked him. "You got about 50 people present. You have to kiss in the hay and I had hay fever and it's about as romantic as being an obstetrician."

Nominated by Reagan to succeed Faith Whittlesey, now assistant to the president for public liaison, Lodge has been an ambassador on two previous occasions. Dwight Eisenhower sent him to Spain from 1955 to 1961 and Richard Nixon sent him to Argentina from 1969 to 1973. In Argentina, he was noted for keeping four embassy staffers working full-time on press releases and photographs of himself and his wife.

Lodge became a controversial figure at his Senate Foreign Relations Committee confirmation hearing, where he said Argentina's president had come to power in 1966 through elections when actually there had been a coup d'e'tat.

Later, as ambassador, he rarely invited representatives of the left-leaning government to the U.S. Embassy. His diplomatic colleagues there were cautious in their appraisals of him. "I've never been able to carry out a serious conversation with him," one ambassador said. "Well, he does have a nice singing voice, if you like that sort of thing," said another.

That was about the time Lodge said that acting was the best preparation he knew of for a career in diplomacy. Last night, he expanded that to take in politics as well.

"It helps you not to be a bore," said Lodge, surrounded by Connecticut cronies who found him anything but boring. "Even if you're not an entertaining actor you should see that you don't bore people."

In Buenos Aires, Lodge often sang to guests gathered around his dinner table.

"He sings beautifully," said Ecuador's Ambassador to the United Nations, Miguel Albornoz, who came down from New York for last night's party.

And he once enthralled a Spanish Embassy party in Washington with his slightly risque' parody of "I Can't Give You Anything But Love."

His wife, the former Francesca Braggiotti of Massachusetts, a professional dancer when she met Lodge in the 1920s, taught their diplomatic colleagues in Argentina how to tango. In Spain, she learned the flamenco. Switzerland, on the other hand, may pose something of problem, since she doesn't know yet what dance she'll do.

"Oh, my God," thundered her husband when someone suggested that she might learn the polka, "she can teach the polka."

Lodge, who tried on his striped pants not long ago and discovered they will have to be let out, said he still believes diplomats must be "formal on occasion."

"We Americans think that it is virtuous to be informal at all times but formality can be very useful at certain times," said Lodge. "We think everybody's got to be folksy at every hour of the day and night and I think that's a mistake."

Guests at the party in the Jefferson Hotel included one-time Reagan campaign manager John Sears, public relations executive Bob Gray, Swiss Ambassador Anton Hegner and Commerce Secretary Malcolm Baldrige, who with Lodge cochaired the 1980 Reagan campaign in Connecticut.

"He's a better actor than I am, though," said Baldrige.

Another guest was Robin Moore, author of "The French Connection," who is a neighbor of Lodge's.

"One thing John has always been good at is in the intelligence field," said Moore, speculating with others on Lodge's duties when he arrives in Berne. "Switzerland is the very center of European intelligence gathering, and John speaks several languages."

Was Lodge about to become a superspy?

"I wouldn't say that," said Hartford real estate developer Jonathan Dugan. "He's activating a sensitive listening post."

"That's all we need," kidded Moore, "a headline that reads 'Top Spy Sent Back.' "

Lodge said his duties would be simply to "increase good relations" and that when somebody told him that Faith Whittlesey would be a hard act to follow, he said he knew.

"But I have an advantage over Faith Whittlesey. I've got Francesca. Faith Whittlesey didn't have Francesca," said Lodge, "and she's my secret weapon, the greatest diplomatic weapon any man can possibly have. She absolutely wows them."