Sen. Bill Bradley (D-N.J.) almost had his brilliant career derailed on Election Day by New Jersey voters, who gave him an unexpectedly and embarrassingly meager 51 percent victory over an underfunded Republican challenger.

The 47-year-old senator is back in Washington now getting ready for the start of his third term, and I was curious to see what effect the close shave had had on him. It is always instructive to see how people react to adversity -- especially those, like Bradley, who had reason to feel they were leading a charmed life.

An All-American at Princeton, a Rhodes Scholar at Oxford, a pro basketball star on the New York Knicks, Bradley was elected senator in his first try for public office at age 35 and, in his mid-40s, was anointed as a future presidential candidate. He certainly seemed to have it all going for him.

But this has been a rotten year for him. Senate reporters noticed that, after playing a decisive and critical role in the tax and economic debates of the '80s, he seemed petulant, defensive and notably ineffective in this year's budget battles.

Some of his friends suggested that on Election Day he was simply the innocent victim of a protest vote aimed at the tax hikes imposed early this year by New Jersey Gov. James Florio (D) and the Democratic legislature. Bradley has both analytical and anecdotal evidence that he was the target for some of that deflected wrath, since he was on the ballot and Florio and the legislators were not.

But he also recognizes that he contributed to his own problems. His ads were too bland, his message unfocused. "I wanted to talk candidly to people about the challenges ahead, and I failed, he said, "and the fault was mine." Having promised early in the year a sophisticated communications effort designed to reach a "segmented electorate," he came away realizing that "unless there is a clear central message," targeted appeals just confuse voters and feed their frustrations.

He also came away understanding a phenomenon that affected far more candidates than himself. "People don't think politicians make any difference in their lives," he said. "They don't believe we talk honestly with them -- and too often, they're right."

It's an international phenomenon, not much different in Poland. "If you're going to take radical economic action, you have to make it credible to the average guy or gal who is struggling under the brunt of it," Bradley said in a statement that might apply equally to the Florio tax hikes and the shock-treatment introduction of market prices by the just-resigned government of Polish Prime Minister Tadeusz Mazowiecki.

Bradley also learned the hard way that distrust of politicians carries over to a distrust of government, even among the majority of voters who see big problems going unaddressed in education, health, crime, drugs and housing. "We {Democrats} are not going to solve it just with a surtax on millionaires," he said. Democrats will have to take a far more critical attitude toward bureaucracy, be ready to "flush out" waste and rigidity, "and that's not easy to do." They also have to have realistic plans for meeting the special needs of the cities and dealing with the growing alienation of the races -- "the problem," he rightly says, "no one even wants to discuss."

The near miss did not deter Bradley from walking his own road on foreign policy. He thinks the military escalation in the Gulf has gone too far, that a combination of economic embargo, measured military threat and stepped-up psychological warfare can work over time. A resort to arms, even if successful, would represent a lost opportunity to demonstrate that in the "new world order," aggression can be defeated by means short of war, Bradley believes.

In the Soviet Union, a country he knows well, he thinks the process of disintegration will continue and that efforts to bail out Mikhail Gorbachev with U.S. aid "will be a waste of taxpayers' money," unless real economic reforms take place and an effective distribution system is developed.

While these views are not new for Bradley, they are stated now with a directness that he has not always shown. And that, too, is a lesson learned this year -- maybe the most important one. "Politicians have to be more willing to take risks," said this hitherto most cautious of operators.

One risk he will not take is running for president in 1992; that is not in his plans. But my guess is that whenever he does run, he'll look back on 1990 -- and his near defeat -- as the year that really prepared him for that challenge. Bradley is one of the great students of public policy; he sets himself subjects to learn, and he does his homework and fieldwork as conscientiously as anyone in public office.

But the lesson the voters gave him this year can be the most valuable one he has ever learned. When his political courage matches his intellect, this man will be tough to beat.