These explanations are wrong. George Bush was picked at the very last moment and largely by a combination of chance and some behind-the-scenes maneuvering. Many Reagan advisers have claimed a deal was never close. The post-convention media commentary has largely reflected this view. In fact, Meese and Deaver have gone so far as to declare that Bush was their first choice all along. I take exception to their account. I saw a very different story unfold, and saw it from a privileged vantage point. From the moment I walked into that suite until the moment Bush was finally selected, I was the only person to remain in Reagan's presence throughout the adventure. With detailed notes to back up my memory, this is what I saw at the dawn of the Reagan Revolution on that long night in Detroit.

Ronald Reagan's search for a vice president started as soon as he clinched the nomination with a string of primary victories in the spring of 1980. Before long, a short list of prospective running mates had been put together, including Howard Baker, William Simon, Jack Kemp, Richard Lugar, Paul Laxalt and George Bush.

None of these prospective running mates were actually ''vetted'' in the way the process works today. Reagan knew all these men in varying degrees, but as was his style, he expected his advisers to do what was necessary to prune the list. The job fell largely to Ed Meese, who knew Reagan's mind better than anyone except Nancy Reagan.

It wasn't until several weeks before the convention that Gerald Ford's name entered into the mix. While it has never been established how it happened, most attribute it to Bryce Harlow, a respected adviser to Eisenhower, Nixon and Ford. Harlow probably initiated the idea in a discussion with his friend, William Casey, who then took it to Reagan and Meese.

As the convention approached, the Ford rumors became stronger. Although Reagan was running even with or behind President Carter in most polls, the idea struck several of us on the senior staff as a highly impractical, if not silly, idea. After all, Reagan and Ford had fought intensely for the nomination in 1976. In 1980, the G.O.P. platform carried Reagan's conservative message down the line. Its foreign policy planks in particular were, under cover of assailing Carter, a de facto indictment of the Nixon-Ford-Kissinger policy of detente with the Soviet Union. Unlike many of his predecessors, Reagan actually believed in the platform and was determined to see it put in place. The platform alone, we thought, would make a Reagan-Ford ticket unthinkable.

In Reagan's suite, however, the unthinkable had become the possible. In less than 24 hours, Reagan was going to have to go before the convention to announce his vice-presidential nominee. And yet for reasons that to this day remain baffling, not only had Reagan given his political advisers free rein to negotiate with Ford, he had also refrained from initiating conversations with other potential running mates. With no alternate plan in sight, it seemed that Reagan was prepared to embrace the wing of the Republican Party that had ridiculed him, probably disliked him and would surely do its best to undermine his agenda.

At 5:50 p.m., Casey and Meese, who had left the suite shortly after my arrival, returned. They seemed pensive. Lyn Nofziger, a longtime aide, joined us a few minutes later, asking, ''What did Ford want?''