LET'S say that Bill Bradley does decide to run for president as an independent. And let's say that he can pull in those massive sums of money he needs to launch this effort and keep it going. Could he succeed? It's conceivable. Teddy Roosevelt came close with his independent-party (Bull-Moose) run in 1912. He got enough votes to knock off the Republican candidate, William Howard Taft, but the Democratic candidate, Woodrow Wilson, won. Thus, Bradley might defeat President Clinton but - like Roosevelt - help elect the GOP candidate. But there are polls that show that there is an immense public dissatisfaction with both parties today, perhaps more so than at any previous period in the history of our two-party system. It's possible that those voters could surge toward a Bradley candidacy and elect him. Indeed, any potential third-party candidate would find this possibility quite inviting. Doubtless Gen. Colin Powell is giving this widespread public uneasiness some careful scrutiny. Right here someone is going to point out that Ross Perot reached out for that dissatisfied constituency in 1992 and after campaigning hard and spending a lot of money picked up only 19 percent of the vote. But Bradley is no Perot. Unlike the brash Texan, Bradley is quiet-mannered. He persuades with thoughtful discussion. His is never the hard sell. It's possible that his approach might be more appealing than Perot's. Bradley the family man, Bradley the great basketball player, Bradley the Rhodes Scholar, Bradley the three-time US senator, Bradley that towering, fine-looking fellow: He just might be what the country is looking for next year. I think that one of Bradley's best possibilities for picking up votes would be among those Republicans who are already expressing their intention not to vote Republican at the top of the ballot if the choice is a Dole, a Gramm, a Buchanan, or one of the other more conservative candidates now seeking the GOP nomination. These voters are the ones who call themselves Republican ''moderates.'' They remain a large, though quiet, group whose voice has long been overpowered by the GOP right wingers. These are the Republicans who usually tell interviewers their heroes are Lincoln and Eisenhower, and who are very comfortable with civil rights legislation. These Republicans aren't happy with Clinton. And Perot really isn't to their liking. But, as of now, they might be willing to bolt their party and vote for someone else - if that someone else would be as attractive and impressive as Bill Bradley. Bradley, too, could bring blue-collar workers to his side. They are his hard-core supporters in New Jersey. Many of these voters have been moving over and voting for GOP presidential candidates of late - beginning with Ronald Reagan. But Bradley's best chance, as I see it, would be if next year's election became one where, after the issues had been debated and chewed over for months, it all came down to a contest where voters were making their choice for, as they might put it, ''the best man.'' This would be a judgment where experience, character, and yes, appearance, entered into the final voter decision. Certainly you can write a scenario where Bradley wouldn't go anywhere if he sought the presidency. He really isn't widely known - although his basketball career helped him with a segment of the voting public. And maybe only liberal Democrats would be attracted to a Bradley ideology, which appears to lean somewhat toward the liberal side of the spectrum. Then, what if there are other candidacies outside the two parties? What if General Powell gets into it or Jesse Jackson or Perot? Well, after groping my way through that cloud of ''ifs,'' I still say that Bradley has the potential for becoming a formidable and, perhaps, winning candidate.