"So I had the president in my chair last week, and I was cutting his hair when I said, 'Well, Mr. President, it looks like I'm going to have a great party. I'm surprised that so many are coming,' " says Milton Pitts, barber to presidents.

"So the president says, 'I'm not, Milt. If you're standing there with a scissors at someone's throat asking them if they'll be coming to your anniversary party, not many people are going to say no."

He's the Chagall of male coif, the Leonardo of political locks. Milton Pitts, 65, barber to presidents, snipper to senators, sympathetic ear to the politically oppressed, celebrated his 20th year of operating in the basement of the Sheraton-Carlton last night, and if his scissors did the talking, his clientele did the walking.

From President Reagan to Defense Secretary Caspar Weinberger to White House chief of staff Donald Regan, the guest list read like a Who's Who in the Washington Book of Power.

"I just washed my hair," Reagan told the mob of fans when he arrived at the Sheraton, "and I can't do a thing with it."

Everyone roared. And then he tried this one:

Question: "What do you call 10 rabbits dancing backwards?"

Answer: "A receding hareline."

The very Reagan crowd went nuts.

Pitts, up on the stage in a barber's chair, was loving every minute of it as the cream of his clientele ate little hamburgers and ice cream sundaes, and sang his praises.

"Milt always makes me look like I have hair and that's something," said Frank Fahrenkopf Jr., chairman of the Republican National Committee.

"He tries to advise me all the time and I reject his advice," said former national security adviser Richard Allen, who has been patronizing Pitts for 16 years. "That's why I look the way I do."

"No. No problem with my hair," said Weinberger, trying to make a break for it. "It's a routine project. He cuts my hair and then I leave."

In a tiny shop in the basement of the White House, Milton Pitts has clipped every president's hair -- with the exception of Jimmy Carter's -- since 1969.

After being pleased with his first trim, Richard Nixon invited Pitts to set up shop at the White House two days a week, where he remained until the Georgians arrived in 1976. Pitts stayed in the Carter White House for 35 days, during which time he learned that the president had quietly used another barber for his first official presidential haircut.

Pitts packed up his blow-dryer and left. He returned at Reagan's invitation.

Here's how he has helped some of his faithful over the years:

* Nixon: "Well, President Nixon was using Brylcreem and his hair always looked shiny. He also had a problem with his nose. His hair was too high in the back and too short in the front. And his sideburns were too thin and too short. I wanted to shorten the distance between the back of his head and his nose so his nose wouldn't look so long."

* Alexander Haig: "He doesn't have much on top. We've had to do a pretty good job to cover that up."

* Gerald Ford: "Well, President Ford used Vitalis. He said, 'Milt' -- he always called me Milt -- 'Milt, let me tell you something about my hair. You see, it's thinning and it's very light. And if you cut the sideburns too thin, it'll look like I don't have any.' So I said, 'Mr. President, you're doing it all wrong.' I took the Vitalis out and started blow-drying it, using hair spray."

* Henry Kissinger: "His hair is pretty curly and coarse. He wants it straighter, so we just blow-dry those curls out."

Pitts says that in the 50 or so interviews he given since he began cutting Ronald Reagan's hair, the main question he's had to field is of the "Does he or doesn't he?" variety. As in dye his hair, that is.

"He absolutely does not!" Pitts says like a man defending his firstborn. "It is not that unusual for a person of his age to still have his natural color. He does have quite a bit of gray up close -- it doesn't show up in pictures or on television -- about 20 percent of his hair is gray. His hair color has not changed any time in the last four years."

Pitts first came to Washington from Greenville, S.C., some 40 years ago. "I really wanted to be a doctor," he explains, "so I took a barbering course so I could work my way through school. But I got to making some good money and started doing better than I anticipated. I got to be pretty good when I was young."

When he was 23, he opened his first shop on Connecticut Avenue, which remained open for 28 years.

By the time Alexander Butterfield asked him to cut Richard Nixon's hair, Pitts already had a blooming barber business at four locations in Washington. "But how can you turn down the president of the United States?" he says.

Pitts has survived in Washington longer than most elected officials. There have been some tough campaigns, though. Three years ago, Pitts and two unisex stylists who were also working in the White House got into a hair-splitting turf battle. It got so bad that James Baker, then White House chief of staff, had to step in and dismiss the unisex cutters. The incident left Pitts the king and Ed Rollins and David Stockman without a hair cutter.

But that's history, and last night, it looked as if Milton Pitts would be trimming the titans for years to come.