For all the talk of this being a runaway, right-wing convention, by Tuesday it had reached the strange position where Ronald Reagan was resisting the clear vice presidential preference of the delegates: George Bush.

The two big surprises of the Republican National Convention have centered around Bush, residual champion of the once-dominant Republican establishment. One surprise is how many delegates at the overwhelmingly conservative convention are willing to put aside ideological scruples and support Bush. The second and more significant surprise is how intractable Reagan has been against him.

That suggests there is still a lot more to be understood about Reagan. While he never has been the fire-breathing ideologue of liberal nightmares, neither is he the cool pragmatist who savors victory above all, as recently portrayed. If he were, there would be no suspense left in Detroit: the Reagan-Bush ticket would be a certainty.

The immediate cause for Reagan's stated opposition is one that seldom gets into the public debate. He feels that Bush's opposition to an anti-abortion constitutional amendment may well violate Reagan's pledge to the "pro-life" movement to select an anti-abortion running mate. That commitment is regretted by many Reagan insiders and perhaps by Reagan himself, but he intends to honor it.

Still, because of Bush's opposition to federal funding of abortions for the poor, a case could be made that he qualifies. Furthermore, when Reagan met privately with right-to-life leaders in California a few days before the convention, he seemed to be preparing them for a possible letdown; he revealed "irresistible pressure" behind Bush.

But Reagan continues to resist the "irresistible" for another and more basic reason than the abortion issue. He and Nancy Reagan have made clear to their aides that they simply do not think Bush is up to the presidency. That judgement, highly colored by Bush's performance in New Hampshire, seems an ineradicable mind set.

There are pockets of anti-Bush sentiment on the convention floor. A poll of his own state of Texas gave 43 (out of 80) delegates to Rep. Jack Kemp. Virginia's delegation is overwhelmingly pro-Kemp, with some members promising blood if Bush is named. An anti-Bush challenge by Sen. Jesse Helms might collect 150 to 200 (out of 1,994) delegates.

But this is far less intransigence than might be expected from the most conservative Republican convention of modern times. The overwhelming choice would be Bush, with heavy support from such supposedly die-hard bastions as Mississippi, Louisiana and even California. The constantly repeated cliche of the average conservative delegate: I'm for Kemp with my heart, but for Bush with my head.

Part of this Bush support stems from the feeling that with all the unfavorable publicity over women's issues in the platform and the image of the yahoos in control, Reagan's options on vice president are limited. But Reagan himself feels no such limitations. "Believe me," said one Reagan confidant, "he likes the platform."

It is not merely a sop to an old and trusted friend for Reagan to say privately that Sen. Paul Laxalt is his first choice for vice president. One intimate friend of the family puts it this way: "The governor and Nancy ask each other 'Why, why, why? Why can't we have our best friend, the smartest, the most loyal, the most attractive?" Quite apart from pragmatism, Reagan would pick Laxalt if given the chance.

Yet, he has bowed to the insistent advice that Laxalt, a conservative and a licensed gambler from Nevada, would be a disaster, Might he then also bow to insistent demand that he swallow his misgiving and take Bush? One of Regan's half-dozen closest associates, a Californian usually considered well to everybody's right, last week told Reagan he must abandon personal perferences and think of nothing but victory (however, he stopped short of overly urging Bush).

Another Reagan unsider thinks a pro-Bush charge here in the next few hours, if led by Gerald Ford, might succeed. But still another intimate thinks it would probably fail. According to his theory, only a convincing argument wiping away misgivings about Bush's presidential capabilities will work.

That is a strange posture for the new leader of a party that elevated Richard Nixon in 1952 and Spiro T. Agnew in 1968 to the vice presidential heights as the inexperienced junior senator from California and the anonymous governor of Maryland. But there is another Republican tradition of not picking running mates for ideological or factional balance. If he follows the preferences of his heart, Reagan is fully in the latter tradition.