Back when he ran the wishbone at Churchill High School in Potomac, Md., the congressman's son had a knack of staying clear of the muddle. His coach figured he was a straight-arrow type, a charmer, dedicated to learning the game and making something of the "God-given talent" everybody fussed about. But it was politics, one old teammate ventured, that ruled the boy: Jeff Kemp knew the importance of being earnest.

"Two kinds ran the show back then," Mike Helman, who played center, recalled the other day. "You had the beer drinkers. And you had those who didn't drink the beer . . . And then, straddling them both, you had Jeff."

Now, eight years later, Kemp plays quarterback for the Los Angeles Rams. You catch him before the game, running drills across the green at Anaheim Stadium, and he looks like a kid who just hopped the fence and beat it around security to center-stage.

This is not Vince Ferragamo, who broke a bone in his passing hand nine weeks ago and has not played since. Nor is it the Rams' other quarterback, Steve Dils, who is most visible charting the offensive play-by-play on the sideline.

Of all people, this is Jeffrey Allen Kemp, 25, eldest son of the Republican congressman from New York who played quarterback 11 years in the AFL and NFL, three years with San Diego and eight with Buffalo. Jeff Kemp's the free agent with great good luck whose emergence as a star is as sudden as it's unlikely.

"Heavens, yes, I'm surprised," Churchill Coach Fred Shepherd said of Kemp's success. "I've felt it and said it all along, there were better passing quarterbacks to play at our school than Jeff Kemp."

But who ever threw the ball at Churchill anyway? The wishbone, in 1976, carried the team to the Maryland AA state championship and an 11-1 record. Kemp spent most of his time handing the ball off to a stable of gifted running backs and threw only two touchdown passes all season. He won no all-league or all-Metropolitan honors, although he later showed off a bit at Dartmouth, breaking the school career mark for passes (398) and completions (198).

Kemp's primary target in college was David Shula, son of Don Shula, the Miami Dolphins' coach. The younger Shula said Kemp was the first person he met when they reported for training his freshman year; later that night, they went out to dinner and talked about what lay ahead. They became best friends.

Shula, 25, now coaches the Dolphins' receivers and is the youngest assistant in the NFL. He knows well the role Kemp is now playing. "We're our fathers' sons," he said. "Both our dads are well known and constantly in the national spotlight. But that shouldn't be an issue if you really get down to it. What you do personally belongs to you, and you should be happy with it."

After the Rams beat the Bears here Sunday, 29-13, Kemp patiently answered questions about the game. He exhibited the elusive grace of one accustomed to the political forum, leavening burdensome questions with touches of wit and irony. When one reporter asked him if his father planned to run for the presidency in 1988, Kemp snorted, shrugged his shoulders and said, "How do I know? How does anyone know what'll happen in Washington?"

One locker away, Ferragamo sat on a stool and unrolled a pair of socks, then worked them on. He squeezed his right hand into a fist, loosened it, then stared down at it as if studying some strange appendage of which he had no control. "The hand," Ferragamo said, "it's nowhere near where it should be. I try to do the little I can and try to get ready. Week to week, I see improvement. But not day to day."

At best gloomy, Ferragamo's mood is understandable. In the first three games of this 7-4 season, he completed 44 percent of his passes (29 of 66) with only two touchdowns and eight interceptions. The Rams' passing offense was ranked last in the NFC.

Kemp, in nine games, has completed 52 percent of his passes and has thrown only four interceptions. Against Chicago, he passed 63 yards to Henry Ellard for a touchdown and led a second-half blowout.

Kemp credited the work of the coaching staff and the play of the defense and the offensive line. He praised the fans and Eric Dickerson, who ran like a sprung bull. And he even mentioned his wife, Stacy.

"She saw all those sacks Chicago was pulling off on TV one night," he said. "She was really worried, but I told her not to be. I knew they were a dangerous defensive team. But you don't go into a game worried."

Calm Kemp. He didn't even sweat when pressed about Ferragamo. Somebody wanted to know if he had established himself as the No. 1 quarterback, and wondered at the presence of Ferragamo on the bench. Kemp made a fuzzy bridge of his eyebrows and gave the question the bent-lip-and-shoulder shrug of one unscathed by the mean, old grind.

"Obviously," he said, "who starts and who plays is the coaches' decision. For me, I have to keep playing well from week to week. And enjoy myself. I don't worry about all that and I can't worry about it."

Ferragamo does. At the beginning of his pro career, he held clipboards while Pat Haden quarterbacked the Rams. Haden hurt his hand late in the 1979 season, and Ferragamo stepped in and led the team to the Super Bowl, passing for big yards and coming on as the newest and brightest star of the NFL.

In 1980, he set a club touchdown record and threw for 3,199 yards, and, in the process, became embroiled in a contract dispute. He once fumed when the Rams pulled him after he had thrown five touchdowns in a rout against New Orleans and replaced him with Haden. He said then, "I remember what it was like being No. 2. I'll never forget how I was treated."

Now, Ferragamo has once again found himself in the shadow of a quarterback who lacks his great passing abilities but leads with intelligence and heart. The fans have taken to Kemp, and so have the players, who are the first to note that the team is 6-2 under his leadership. Ferragamo, it appears, has plenty reason to fret.

"Emotionally," he said, "I don't know how I feel. Nobody really knows if the position will be mine when I return. It's hard to say because you never know when a guy gets hurt, especially at quarterback, whether or not he can come back and be No. 1 again. I think a lot depends on the mood of the team and how it responds. The guy who does it for you is the guy you want to keep playing."

It's easy to figure. Ferragamo's out, Kemp's in and, as Coach John Robinson put it, "The Rams are on a roll, baby."