Phoebe Tyler is running around the country campaigning for Jimmy Carter.

You know Phoebe, that silly, vain, rich, vengeful, snobbish matriarch of the soapy "All My Children." You'd never think she'd be for Carter. Not in a million years.

"Well," says Ruth Warrick, who is also Phoebe Tyler and can't always tell the difference, "you know Benny Sago is a very good influence on me, uh, her . . . at first she was so snobbish that I wouldn't let him in the library in his blue jeans, but now he's not only my, uh, her chauffeur, he's her best friend. He'd be more for Carter."

There's nothing silly or vain or snobbish or vengeful about Ruth Warrick, although she probably is rich, thanks to Phoebe.

She is a sensationally young-looking 64 years old, has played Phoebe so long (11 years) that her own intelligent, passionate, socially conscious character is beginning to make inroads into the troublemaking, self-centered soap opera role.

And of course it is Ruth Warrick who is campaigning for Carter while Phoebe Tyler is on a nationwide tour promoting "The Confessions of Phoebe Tyler," a book about Ruth Warrick.

"Well, you know I have to be careful when I'm on a radio or TV show," says Warrick, "equal time and all, so I just start talking about my good friend Miz Lillian and how I hope she'll be all well soon enough to dance at Jimmy's inaugural." She innocently bats her long, thick, not altogether natural looking eye lashes. She is chicly dressed in black silk with a dazzling red and black handpainted Chinese-style quilted jacket, designed for her and Phoebe Tyler by Ana Colon.

When she doesn't have to worry about equal time, she doesn't.

"You know I've known Jimmy Carter for years," she says. "I'm very, very definitely a Carter person," she adds unnecessarily.

"Of course I also know Reagan. I've known him all my life." She pauses. "And although he is a very personable man, and a likeable person . . ." She pauses again and with all of Phoebe Tyler's famed contempt she says cooly, ". . . he's like a drugstore cowboy cutout . . . He was up on his lines during the debate Tuesday night, but he can learn any script you give him." Moreover, she thought that he'd gotten "a little flustered" here and there. "He got a little tired," she says, with no sympathy whatsoever in her voice.

When Phoebe Tyler puts her mind to something, well, you'd have thought she was talking about her ex-husband's second wife Mona. Hard woman, that Phoebe.

Ruth Warrick is not a hard woman at all, although her own life has been a bit of a soap opera itself, as she is the first to admit.

Her movie debut was in "Citizen Kane" playing Orson Welles' first wife.

A pretty, aristocratic-looking actress, she had no dearth of roles -- from Walt Disney ("Song of the South") to TV's "Peyton Place." She also had several more or less unsuccessful marriages and a memorable affair with Anthony Quinn, all of which is catalogued in Phoebe Tyler's confessions.

Her greatest success is without doubt Phoebe Tyler. For a "negative" character, Phoebe generates enormous love, and strangers are always hugging her, touching her, "Oh Phoebe, you were so awfully mean," or "Oh, my daughter will never believe I met Phoebe Tyler," or "Listen, you've got to know your husband is going to steal you blind. He's a crook!"

"Well," huffs Phoebe-Ruth, "I don't listen to that kind of talk at all. Why he is a gentleman and a scholar, a man who has devoted his life to academe, I won't listen to any talk against him at all . . ."

Actually, that is the most asked question, "When are you going to find out the truth about your husband?"

Phoebe huffs.

Ruth twinkles.

Ruth Warrick is a Missourian. It was at the University of Kansas City that she decided to be an actress.

"You know, people have the idea that if you really want to do something or be something then you probably shouldn't ," she says. But after a small nervous breakdown "from exhaustion and other things," she says, it was doctor's orders that gave her permission to do what she wanted -- act.

In addition to "All my Children," she will occasionally take time off to do a traveling show, but she can't leave Phoebe behind. She was in Houston, several years ago, with a company doing "Irene." The costumer could only murmur, "Imagine. Me dressing Phoebe Tyler. I'll have to tell my brother."

"Your brother ?" asked Warrick , surprised. "What does he do," "Oh," said the dresser, "he's a longshoreman." "That," says Ruth Warrick, "was how I began to learn about the importance of daytime."

Ruth-Phoebe is sitting in the canteen at NBC's Washington headquarters, where she has done a live radio show. "All My Children" is an ABC show. Never mind; as she sips her tea, an employee waves from across the room, "I always watch you." A woman sits down opposite, a broadcast engineer. "Oh, I just wanted to say hello so I could tell my little girl I met Phoebe Tyler."

Warrick believes Phoebe did much to bring soaps out of the closet. "Why, we [daytime TV] account for 75 percent of [TV] profits," she brags cheerfully. "All My Children" vies at the moment only with "General Hospital" as the most-watched soaper.

"Now nobody is ashamed to say they watch . . . why we generate more dollars than anything on the entertainment horizon, even records."

She tells this story about actress Joan Fontaine: "She had just come back from a prestigious stage engagement in England and was shopping in Bloomingdale's. A sales person looked at her and asked, 'Didn't you used to be an actress?' Fontaine called up her agent and said, 'for heavens sake, get me on a soap so people will know I'm still around!'" which is why Joan Fontaine turned up briefly on "Ryan's Hope."

In addition to Phoebe and her "very real" family on the set, Warrick has three grown children of her own: a clinical psychologist son in Bethesda, a musician daughter in the Midwest and a disc-jockey son in Colorado. And two grandchildren.

Her pet avocation is teaching acting to disadvantaged blacks and Hispanics at the Julia Richmond School in Manhattan. ("We write soap operas and give them," she says. "They're a wonder.")

Ruth Warrick decided to help the Carter campaign in 1976.She'd heard Miss Lillian watched the program and placed a call.

When she had identified herself as Ruth Warrick, she hadn't gotten very far. Miss Lillian wasn't there, a voice said, and was about to hang up.

Then, as she describes it in her book:

"This is Phoebe Tyler calling."

". . . Hey, it's Phoebe Tyler! Why Miz Tyler, you want Miz Lillian's private number?"

"I dialed it, and Miss Lillian answered.

"'This is Phoebe Tyler,'" I said.

"'. . . Why, I don't believe it,' she said, 'I was just now watchin' you on the TV. You were bein' so mean to Linc and poor Kitty. How come you ah such a bee-utch?'"

And they've been fast friends ever since.