Once, Tom Bradley, the mayor of Los Angeles, said of fund-raising, "I hate it. I have to tell you, there's nothing I hate worse. The fact that I don't like it doesn't mean I don't do it well."

Well, laughed Bradley last night just before two receptions here to beef up the coffers for his campaign to be the next governor of California, "I was speaking more of personal involvement, the calling-on of people, that begging. I don't know any politician who likes that. I like more-personal confrontations, so you can meet and exchange views."

By the end of a two-day Washington whirl, the man the polls say is the most popular politician in California, and the front-runner so far to succeed Gov. Jerry Brown, had reinforced his skill as a solicitor of dollars, his attractiveness as a national politician and his preference for personal contact.

Yesterday evening, Bradley stood in a dark room at the Jefferson Hotel, greeting 65 lawyers, lobbyists and corporate executives invited by the law firm of Patton, Boggs and Blow. Then he stopped by another dinner to speak to Reps. Jim Wright (D-Tex.) and Tip O'Neill (D-Mass.), and then walked into a crowd at the home of Rep. Charles Rangel (D-N.Y.), where the 80 people invited by the National Coalition of 100 Black Women had mushroomed to 300 in just nine days.

Everywhere there were handshakes and a pledge by Bradley to win the election as a testament to the California, and the American, Dream. "My family brought me to the land of opportunity when I was 7. They didn't make it as far as they wanted to go but it made the doors open for me," said Bradley. At the Boggs party there was applause; at the Rangels', amens. "This is a crusade," said Jewell Jackson McCabe, president of the coalition,shouting from the Rangels' staircase. "This country needs a signal -- a man who stands for fiscal responsibility as well as compassion."

Bradley, 64, has been mayor of the country's third-largest city since 1973. If he wins he would be the first black ever elected a governor. That's the American dream. Yes, he said emphatically, that still carries a certain symbolism in the 1980s. "I have not emphasized the racial significance in my campaign but I do see some positive ramifications. Not only in this country, but worldwide, it would be further realization of the American dream. When I was first elected, children of every race saw something good in it. If Tom Bradley could do it, overcome all his obstacles, then I can do it," he said.

A tall, trim man, with deep eyes that dance from a half-mast position, he is pushed by his desire to serve. After he finished UCLA, where he was a track star, Bradley worked for 21 years on the police force, went to law school at night, practiced for a while, then served six years on the City Council. He lost his first bid for mayor to Sam Yorty but has won the three elections since. "I have spent my whole life in public service. In each case I tried to expand the opportunity to serve more people," he said. Retirement doesn't seem like a reward. "I have always enjoyed the involvement, the activity, the challenge."

Bradley's Washington visit started with a dinner Monday night at the Georgetown Club given by Charles Manatt, chairman of the Democratic National Committee. "We may have raised close to $30,000. I like his consistency, his style, the kind of quiet leadership, and his ability to solve problems, like his leadership to get the Olympics to Los Angeles in 1984," said Manatt last night. At the Rangels', former vice president Walter Mondale left a $1,000 check from his own Political Action Committee funds. In the period from October to December of last year, the Bradley committee raised more than $1 million, and Bradley projects he will need $5 million to $7 million to beat his Republican opponents, who have raised almost double his amount.

At a time when the economy dominates most voters' decisions, Bradley says he has balanced the budget eight years in a row without asking for new taxes, developed Los Angeles' fiscal stability so the city has a Triple A rating on the bond market and developed 200,000 new jobs for the city. "I am able to pull these people and resources together in a low-keyed, behind-the-scenes manner. People say Tom Bradley doesn't make a lot of noise, but I don't care who gets the credit," said Bradley, his voice as moderate as his views.

At home he has received some criticism from minorities for his ties with the downtown business establishment. But Ron Andrade, of the National Congress of American Indians, last night cited Bradley's formation of a citywide Indian commission as one of his achievements. John Olson, a Washington attorney, defended Bradley's approach. "He's from a different generation, when you have to have self-control."

Though his campaign looks winnable, the New Federalism has him worried, and he spent some time on the telephone yesterday with Reagan officials. "Most cities don't have problems accepting the responsibility if they have the funds. But if the resources diminish, I'm apprehensive. In the proposed budget California would have to come up with one to two billion of additional revenue to deal with a whole range of things," said Bradley. His popularity among Republicans was noted last night. When he was leaving the Boggs reception, he ran into Attorney General William French Smith, who greeted him like an old friend.

The current president, a veteran of the job Bradley wants, once said the governor of California was the second-most-important executive job in the country. Reminded of that, Bradley laughed off the suggestion that he might want to make Washington more than a place for meetings and fund-raisers. "No, no, I am concentrating solely on this at this time," said the man they were already calling governor last night.