In some editions yesterday, the introduction to the profiles of Barbara Mikulski and Michael Barnes implied that they were the only two Democrats pursuing the Maryland Senate nomination. Harry Hughes, who is also seeking the Senate seat, was the subject of a profile here when he was running for reelection as governor.

In some Republican households it might have caused an uproar. But when 17-year-old Michael Barnes wanted to go campaigning for John F. Kennedy, he doesn't remember its causing too big a controversy. His parents were "Mathias Republicans," very interested in politics, and perhaps they were pleased that their younger son was taking an interest too.

Barnes' father came to Washington during World War II to work in the Office of Price Administration, where "he knew them all -- John Kenneth Galbraith, Richard Nixon." His closest friend was Harold Leventhal, general counsel to the Democratic National Committee and later a federal judge himself. After OPA, John Barnes went to work for AT&T and became general counsel of C&P Telephone. The family moved to Cardiff Road in Chevy Chase, where not so long before, the trolley had taken summer excursionists out to Chevy Chase Lake; the subdivision backed up on Coquelin Terrace, where young members of Congress such as Hubert Humphrey and George McGovern lived.

sk,3 Michael Barnes became more involved in politics when he graduated from Landon and went away to the University of North Carolina. He worked for Richardson Preyer's unsuccessful governor campaign in 1964 and that summer, with his father's help, became Harold Leventhal's "briefcase carrier" at the national convention in Atlantic City. He was in the room with Bull Connor and Joseph Rauh as the young attorney general of Minnesota, Walter Mondale, mediated the controversy over the Mississippi Freedom Democratic Party.

sk "After that convention I was convinced it" -- politics -- "was something I wanted to do." That fall he spoke for the Johnson-Humphrey ticket before North Carolina Rotaries and the Elizabeth City White Citizens' Council -- by no means unhazardous duty.

sk,3 Politics was not all Barnes kept busy with. He was an English major, and read the great English and American novels; he was on the swimming team, in breast stroke and distance races; he had his own program on the college 50,000-watt radio station, "Jazz From the Hillside." He was busy too, if not entirely hard-working, at the Institute of Higher International Studies in Geneva in 1965-66: he did a lot of skiing, went with 10 other students to Morocco over Christmas, chaperoned a tour group of southern college girls and traveled around the Mediterranean. In Athens he finally met the daughter of the man his father had car-pooled with for 14 years; they were married in Washington in 1970.

About to be drafted, Barnes enlisted in the Marines in 1966. "I was opposed to the war, as were the vast majority of Marines, especially those who had been over there." But he never went. After Parris Island he was assigned to Quantico and edited the Quantico Sentry.

sk After Quantico, it was back on the fast track. He started George Washington Law School. Working the summer at a law firm, he was asked by LBJ aide Harry McPherson to write a speech; McPherson, a brilliant writer himself, got him a job on Edmund Muskie's staff. This was in 1970, when Muskie was the front-runner for president, and Richard Nixon seemed to be reeling. "We thought we were going to walk into the White House. I thought, here we go."

But his path upward took different, unpredictable channels. When Muskie lost, Barnes went to Covington & Burling, Washington's largest law firm. "Very good experience," he says. "They leave no stone unturned for their clients." He did corporate tax work, some estates, some antitrust and trademark and copyright -- and found time somehow to be active in Montgomery County Democratic politics. In 1975 Gov. Marvin Mandel owed the county some recognition, and Barnes was asked whether he wanted a part-time seat on the Public Service Commission; surely to the surprise of his associates at Covington and Burling, he did. To help him get by, Democratic National Chairman Robert Strauss gave him a part-time job as staffer for the platform committee.

In the normal course of things, that could have led to a job in the Carter administration, but Barnes didn't want that; he stayed at the PSC, and now stresses his commitment to and knowledge of Maryland. He was also thinking of elective politics. 1978 was a Republican-trending year, and Montgomery had a new congressman, Newton Steers, with the kind of moderate-to-liberal voting record the county has always liked. But Michael Barnes ran against him and won, ringing doorbells and exploiting Steers' weaknesses shrewdly. Only two years later, after the Reagan landslide, some House Democrats ran him for chairman of the Latin America subcommittee, and he won again, becoming a national Democratic leader on a key issue. Some wonder why he is giving up so much to make a difficult race. But this young man who has been in and out of the top levels of American politics over the past 22 years seems confident that he has found another path upward.