As Ronald Reagan breezed to the Republican presidential nomination in the spring of 1980, his pollster, Richard B. Wirthlin, surveyed voters to find out who would most strengthen the ticket as Reagan's running mate. The winner was George Bush, who had clung for months to a desperate candidacy in the hope that it would land him the No. 2 spot.

Reagan didn't think much of Bush in those days. Visual images are vital to Reagan, and his memory of Bush was of their debate in Nashua, N.H., when Reagan proclaimed ownership of the microphone in one of the most memorable moments of presidential politics. Afterward, Reagan could not understand why Bush had sat there and let him steal the show. He told an aide that Bush lacked "spunk."

Reagan's impression was reinforced when Bush backed down in another confrontation in the Texas primary, this time in a television exchange from separate locations. "He just melts under pressure," Reagan said of Bush. It was this impression of Bush's weakness that led Reagan, at the GOP convention in Detroit, to embark on the ill-advised adventure of exploring a "co-presidency" with former president Gerald R. Ford. Only after this improbable idea collapsed, and time was running out, did Reagan finally agree to Bush.

In his confrontation with CBS News anchorman Dan Rather last week, Bush may not have answered lingering questions about his role in the Iran-contra affair. He may not have resolved other doubts about his judgment and vision, even for those who care little about the Iran issue. And in nearly eight years as a profile in political deference, Bush has yet to demonstrate that he can remotely match Reagan's reach in attracting independent or working-class Democratic voters.

But, with a big assist from Rather, Bush has at last confronted and banished the specter of Nashua. No one is more delighted than Reagan, whose performance at Nashua did much to create what became inelegantly known as the "wimp factor." After Bush's bashing of Rather, the president was said to have remarked to an aide, "I didn't see any wimp in that."

In fact, the "wimp" accusation has always been a bum rap. Bush does not rival Reagan as a communicator, and he may be unappealing to voters seeking a new political direction, but there has never been any question about his physical courage. He is, along with his principal GOP rival, Sen. Robert J. Dole of Kansas, a genuine war hero. What he lacked at Nashua was ability to think on his feet when confronted by an angry Reagan, arguably one of the best political performers of the age.

Reagan isn't running this year. In the last few months, however, as Bush's foes have made Iran-contra a dominant issue, the president has developed a keen interest in the outcome of the Republican presidential race. He remains officially neutral, because he believes it is the right thing to do and because he needs Dole's help in the Senate. But he is rooting for Bush. His true feelings emerged at a "photo opportunity" last week when he said Bush had been "exactly right" in refusing to disclose the advice he gave -- or didn't give -- the president on the wisdom of selling arms to Iran.

Reagan knows that he cannot anoint Bush as his successor. If Bush is to win the nomination, he must earn it and, if he doesn't win it, Reagan is enough of a party man to campaign for whoever defeats him. In the immediate future, like final-year presidents before him, Reagan will focus on the international arena. If he and Soviet leader Mikhail Gorbachev advance along the path of a strategic nuclear arms treaty, the result should give Bush a boost.

But everyone who knows Reagan recognizes that he is most effective when fully engaged on behalf of a cause or candidate for whom he really cares. The caring can be the crucial difference between doing what duty requires and making the added speech that could put a candidate over the top in a close election campaign. Reagan values his legacy and Bush's loyalty and has long wanted to see the vice president succeed. But there is an added dimension now. Reagan respects Bush for his performance in the clash with Rather. In the process, Reagan has come to care for Bush.

Revelation of the Week: Explaining at a briefing last Wednesday why the Nicaraguan contras need more supplies, White House spokesman Marlin Fitzwater said, "What happens is, when you get short on bullets, you fire your gun less."