Phil Osborne, the owner of an Atlanta travel agency, remembers the young Mike Barnes quite well: dynamic, responsible and "a bit ivory towerish." He decided to hire the 22-year-old Barnes to lead a group of college women on a tour of Europe in 1966.

Now, four-term House member Michael D. Barnes jokes that it was the best job he ever had -- a young, single man getting paid to take the "grand tour" of Europe with 22 young women.

Some say that the 42-year-old Barnes, who is running for U.S. Senate in Maryland, has always led a bit of a charmed life.

As a young man he moved easily into the national Democratic network and on to Congress -- he worked for former senator Edmund Muskie (D-Maine), the Democratic National Committee, and Covington & Burling, a well-known Washington law firm -- bypassing the political clubhouses, county council and state legislature route through which many Maryland politicians trudge.

Now Barnes is trying to prove that he is more than Montgomery County's man on Capitol Hill -- trying to expand his appeal beyond the city's blue chip legal parlors and one of its traditionally more liberal suburbs.

The critics complain that he is a dispassionate politician born with a silver spoon in his mouth -- a fair-haired preppie, they say, with no affinity for the poor farmers, struggling shopkeepers and unemployed steelworkers in grittier parts of the state.

Barnes conceded that his appeal throughout the state is to "the intellectuals . . . the type that watch "MacNeil-Lehrer Newshour ."

But he added: "We are what we are. I wasn't born in a log cabin. I think my record in Congress indi- cates I understand the needs of people less fortunate, and I've been active in programs that will help them."

Statewide polls taken during the past four months show Barnes significantly behind Rep. Barbara A. Mikulski of Baltimore and about even with Gov. Harry Hughes in the race for the Democratic Senate nomination.

Barnes' supporters insist that he can win the Sept. 9 primary because they say his credentials reflect qualities Maryland voters traditionally seek in their U.S. senators. Barnes is staid, academically well credentialed, a House Democratic leader on Central America and an alumnus of a prominent Washington law firm.

Also, Barnes' campaign strategists say he can appeal to a cross section of voters. He has gone to bat for federal employes and crusaded against drunk driving -- major concerns in Maryland that cut across ideological lines.

Also, his supporters say, his two years as a Marine and his appeal as a family man -- he is married and has two daughters -- will make him an attractive candidate in conservative areas, despite his liberal voting record.

In contrast to Mikulski, who has roots in the rough-and-tumble world of Baltimore ethnic politics, Barnes is a reserved and private man who does not appear to generate the spontaneous intimacy that many politicians establish with strangers.

Barnes' personality and political successes have worn well in his district, where many voters are government workers who focus closely on national and international issues and have a tradition of electing good-government politicians.

Although low-key in personality, Barnes is not lacking in drive, discipline and unabashed confidence. As part of his standard campaign message, he frequently tells audiences: "The Almanac of American Politics says I'm among the two dozen most influential congressmen."

Barnes was born in Washington at the old Garfield Hospital, near where the Washington Hilton now stands. He was one of two boys. His father, a liberal Republican and a prosperous executive at the Chesapeake & Potomac Telephone Co., was a quiet, serious man who had an enormous influence on Barnes.

His father's death last summer, after a lengthy illness, caused him to rethink his life, Barnes said. "I really made the decision to run for the Senate as I watched my father die," Barnes said. "Life is very short . . . . You realize that you're next up at the window."

Barnes attended the private Landon School in Bethesda and then went to high school at The Principia, a Christian Scientist boarding school in St. Louis. At both schools he was active in sports, particularly swimming, football and fencing. "He was an average athlete . . . but he was the kind a coach loves, because he gave 100 percent all the time," said Bill Simon, a coach at The Principia.

His interest in politics -- and the Democratic Party -- was sparked by the 1960 presidential campaign of John F. Kennedy, and he spent hours handing out leaflets for Kennedy in Montgomery County. After the campaign he attended the University of North Carolina, where he talked often and enthusiastically about national politics, according to John Sheldon, a former Delta Epsilon fraternity brother; Barnes was a fraternity secretary and rush chairman.

After college, Barnes attended the Institut Universitaire des Hautes Etudes Internationales in Geneva, and he was swept away by Europe. His first letter to his fraternity brothers was a 50-page, single-spaced, typewritten chronicle of his adventures there, Sheldon recalled. Barnes seemed fascinated with foreign affairs even then, and that interest has continued throughout his years in the House.

After returning home, he served in the Marine Corps and then attended Georgetown University Law Center. But politics, particularly international affairs and the social programs promoted by Kennedy and others during the 1960s, continued to capture his interest.

Opportunity knocked in 1970, and Barnes parlayed his Washington connection to land a job as a speechwriter for Muskie's presidential campaign, which was managed by Berl I. Bernhard, a partner in the law firm where Barnes was a clerk.

Muskie's bid for the 1972 Democratic nomination stumbled and died in the snows of New Hampshire, and Barnes decided to hang his shingle with Covington and Burling.

In 1976 politics called again, and Barnes signed on as executive director of the Democratic Platform Committee. Ray Rasenberger, a coworker, recalled that Barnes was perfect for the post because he was fastidious and methodical, leaving no detail to chance. "There was nothing hit-or-miss in the way he does things," Rasenberger said.

A few months after the election, then-Gov. Marvin Mandel appointed Barnes to the Maryland Public Service Commission. For more than two years Barnes carved out a role as a consumer advocate, and in 1978 he stunned friends by announcing that he would challenge one-term GOP congressman Newton I. Steers for the Montgomery County seat in Congress.

At the time, Steers appeared to be popular and Barnes was a rookie candidate in elective politics. But he launched an aggressive attack against Steers, sparking an unexpectedly lively and vicious campaign that ended in an upset victory for Barnes.

By 1980, Barnes was ready to disprove many notions that he was a political novice. It became apparent that year that his reelection campaign could be blunted because of the unpopularity of President Carter's policies. Barnes began to distance himself from the Democratic standard-bearer, and he ultimately emerged as the leader of the "Dump Carter" effort leading up to the Democratic National Convention in New York.

Although the drive was unsuccessful, it thrust the freshman Democrat into the national limelight and Barnes won a second term.

After the election, Barnes, an outspoken advocate of human rights, was tapped to be chairman of the Foreign Affairs subcommittee on Western Hemisphere Affairs, a post that propelled him into the spotlight as a harsh critic of the Reagan administration's policies in Central America.

Barnes' attacks have drawn fire from conservatives, and he has used the counterattacks to emphasize his role as one of several leaders of the persistent, though generally unsuccessful, Democratic effort to block U.S. aid to contras, the anticommunist insurgents trying to overthrow the leftist Sandinista government in Nicaragua.

Barnes hopes that his campaign theme -- "He Stands Up for What's Right" -- will stir voters enough to give him a come-from-behind victory in the race, much like his underdog win over Steers eight years ago.

"Everyone said I couldn't win, but I did," Barnes said. "And I can do it again."