By Richard Blow

  Of all the celebrities making their mark in world politics today, the most persuasive is a 39-year-old musician once known for popping out of a giant lemon to make his entrance on stage.  He is, of course, Bono, and in the 20 years since he and U2, the band he sings in, first started touring the United States, he has become rock's most powerful voice.

  In the early days, the Irish quartet won converts with a dramatic, propulsive sound - so much more optimistic and spiritual than the punk that preceded it - and passion.  Rather than insulting audiences, U2 inspired them.  By 1989, with the release of The Joshua Tree, U2 had established itself as the most popular band in the world.

  And perhaps its most political. U2 treated the stage as a soapbox, singing about U.S. policy in Central America, violence in Northern Ireland, and apartheid.  Bono himself was active in Live Aid, Amnesty International, and Artists against Apartheid.  In time, the band became an object of satire, its ideology threatening to shout out its music.

  So, in the '90s, U2 radically remade itself.  On its Zoo TV and Pop Mart tours, the band staged a carnival, blending in spectacle, such as the giant lemon.  "Zoo TV was about throwing off our moral baggage," Bono says.  Politics was never far away, but the angle of approach became oblique.  At some shows, the band aired footage from the war in Bosnia.  Bono, meanwhile, made a habit of telephoning the White House from the stage and broadcasting the conversations.  George Bush, who had probably never heard of U2, did not take the calls. Bill Clinton, who was a fan, did - a fact that marked a new challenge for the group, the transition from rock rebels to political authority figures.

  It's a role Bono has taken to.  Though he's busy working on a new U2 album, to be released this fall, and a film, he has thrown himself into Jubilee 2000, an international campaign to pressure western banks and governments to forgive the debts of Third World nations.  The loans, proponents of debt forgiveness argue, were often made to corrupt dictators who used them to line their own pockets.  Now, new governments are suffocating under the weight, unable to pay back the principal and diverting scarce funds away from their citizenry to make interest payments to wealthy westerners.  For Bono, Jubilee 2000 is not only a political issue, but a moral one: How can westerners justify human suffering in the name of loan payments?  In an increasingly interconnected world, he argues, maintaining an economic stranglehold on developing nations will haunt us sooner rather than later.

  The rock star's crusade is gaining momentum.  Last fall, the G7, a group of Western governments, agreed to cancel $70 billion in loans.  Much credit goes to Bono, who has made pilgrimages to Rome, Wall Street, and Capitol Hill to fight for his cause.  After Bono met separately with the pope and President Clinton, both men announced their support for Jubilee 2000, and Clinton, citing Bono as an inspiration, declared that his administration would officially support debt forgiveness.  In an exclusive George Interview, Bono reveals the behind-the-scenes details of his social activism.