Once he was the first popularly elected chairman of the Board of Supervisors in the most affluent and populous county in Virginia. Now Fred Babson sits in a small poster-bedecked campaign office in Arlington and thinks about the six men and one women running against him for the Democratic nomination for the U.S. Senate.

"I was on the Board of Supervisors and doing quite well when Clive (DuVal) first ran for office and Carrington (Williams). Rufus (Phillips) I'd never even heard of - he came on after my time. I was in public office before any of these guys were, I guess I'm the only one remebers that."

Now Fred Babson is trying to rekindle those memories as he has for the last yeat, and turn them into votes in Fairfax. In his former seat of power, a man who announced his candidacy a mere seven weeks ago is running ahead of him.

Babson has been traveling the state for a year now, attending feasts and functions that have ranged from the Pulaski precinct potluck supper to the triumphant festivities held for Chuck Robb the day he was inaugurated lieutenant governor.

On that bright cold morning in January. Babson watched as Robb and his retinue left for the inaugural stand,he stood outside the banquet room and tried to explain to a potential supporter that no, he was not Peter Babalas, state senator from Norfolk but Babson, Fred Babson, and he was running for the U,S, Senate.

"It's been a gradual process of letting people know I was alive again," said the man who last held elected office eight years ago. "Six months ago it was 'gee, where've you been Fred?" But now there is very little feeling left of 'who is he?'"

Most political observers keeping tabs on the crowd field of Democratic hopefuls do not share his confi-now know who he is. It has not stopped Babson, who is running on the money that he made as a condo-minimum developer in Virginia Beach and on the sale of an office building he owned in Fairfax.

So far, Babson said, he had contributed $99,000 to his campaign, in which he is stressing his leadership abilities. He has not been involved politically since he left his job as Fairfax County board chairman in midterm citing the need to earn more money.

"I always intended to run for the U.S. Senate," Babson said recently. "I had to take a sabbatical from politics to make some money to get in a financial position where I could afford to fun.I'm a single-minded individual. If I'm in politics, that's all I live, eat and breathe. So when I got out of politics for one purpose - to make some money - that-s all I concentrate on."

In the two areas of the state which Babson can call home, however, some observers feel that his concentration may have backfired. Remaining apart from the political scene in Virginia Beach "has made it much more difficult for him to attract supporters," said Bernard G. Barrow, a Democratic member of the House of Delegates from that area. In terms of committed delegates candidates to thie Saturday's statewide mass meetings. Babason came in second in Virginia Beach, behind Norfolk City Councilman Conoly Philips.

In Fairfax, Babson came in seventh among the eight Democratic hopefuls for whom would-be delegates "prefiled," while Colony Philips, a born again Christian and lately-arrived political candidate came in fifth.

Former attorney general Andrew Miller, state Senator Hunter B. Andrews and feminist Flora Crater are the other candidates in the race, aside from the two Phillipses, Williams, and Duval.

Babson blames his relatively poor showing on the fact that northern Virginia has managed to supply the race with four of its eight contenders excluding himself, and, that against such competition, the odds were stacked against him.

Democratic stalwarts in Fairfax agree, but add that a certain resentment has been harbored against him, since he abdicated the chairmanship in 1970.

"A lot of people worked very hard to get Fred elected to the chairmanship." said one veteran party worker. He left a lot of hard feeling when he quit. He said he quit because he needed the money, but he knew what the salary was before he took the job.

Nevertheless it is so to the job he did as board chairman and the host of other positions he held at the time that Fred Babson turns for support of his contention that he is the leader Virginia is looking for.

While Babson feels the nomination will be won on the themes of personality and "winability," he contends that he took the lead among the candidates in talking about the issues. Although he is opposed to the Panama Canal treaties, he finds himself in general with President Carter on most national issues. He is, he says, aliberal on social issues and fiscal conservative. But leadership, he says, is the main theme of the campaign.

"Let me put it this way," he said "I think I have more leadership ability than they do. Thy're certainly not dismal failures by any means, but I think I have more leadership."

He counts off his accomplishments like beads on a rosary. "I was chairman of the Board of Supervisors, I was chairman of the board of virtually everything I ever served on, Metro, the Council of Governments, it's a long list,. transportation planning board, NVTC (Northern Virginia Transportation Commission) and so forth down the youth council, or up to the youth council.

"I've always been elected to head the organization that I'm involved in, and the fact that Metro under my leadership, they said it was something that never could be accomplished . . . but I'm immodest enough to think that I was instrumental in putting this thing together, and digging the first shovel of dirt."

He passed for a moment as a real estate agent came bustling in to show off the space to a future client. Look at Andy Miller," sadi Fred Babson of the man considered one of the front runners in the crowded field. "All he ever was was attorney general."