Opinion is growing among President Reagan's supporters, including administration officials, that he must soon do what he should have done months ago: pardon Rear Adm. John Poindexter and Lt. Col. Oliver North.

Resistance to that daring proposal remains intense among the cautious moderates, mainly veterans of Capitol Hill, who dominate Reagan's senior staff. If their assertions are true that the word ''pardon'' has passed no lips in White House meetings, the president's men are far behind the power curve.

But failure to grant pardons, preferably before either North or Poindexter is indicted, would ensure endless airing of U.S. government secrets under unpoliced auspices of the uncontrolled independent counsel. It would aggravate the damage to the administration caused in no small part by the president's own responsibility for having allowed Iran-contra to expand to its present exaggerated proportions.

Reagan's culpability for this damage is clear from the testimony of North and Poindexter. The case can be made that the White House overreacted when the arms diversion ''smoking gun'' memo was discovered Nov. 25.

The decision to fire North, a decision bearing fingerprints of then-chief of staff Donald T. Regan, is now viewed in retrospect by objective insiders -- such as Maj. Gen. Brent Scowcroft, a member of the Tower Board -- as lacking in rational foundation.

But in hindsight, the greatest mistake was criminalizing the proceedings. Once North and Poindexter were, to their astonishment, made targets of criminal prosecution and put in the hands of the independent counsel, the paralysis of the administration was ensured.

So began weeks of hand-wringing by the president's friends and eager anticipation by his foes. Without the criminal menace, Poindexter could have said to the world what he privately told a senior White House aide the night of Nov. 25: ''I gave the president insulation.'' That was the statement exonerating Reagan which the criminal proceedings prevented from being uttered for more than seven months. That the admiral did not consult the president on so grave a matter is extraordinary, but it had nothing to do with criminality and everything with judgment.

Late last year, a quick end to the paralysis was offered the president by a longtime Reaganite: pardon both men, on grounds they were performing duties in support of national policy. When the idea was taken to Don Regan, he dismissed it peremptorily. Terrified of the Watergate precedent, the White House high command confused efforts to keep the contras alive with the top-level cover-up of a political burglary.

The long shadow of Independent Counsel Lawrence Walsh's mini-justice department still blots out the sun from the White House. When we asked why the president was so reticent about joining other conservatives in commending North's salutary performance, a senior Reagan aide replied: ''You know, we have an independent counsel down the street.''

Preoccupation by the president's men with trying to save their boss has led to further injustices to his vulnerable and troubled former aides. On the very day Poindexter's sworn testimony removed whatever slim threat of impeachment was in the air, the official White House statement accused him of not telling the truth and doing a ''disservice'' to Reagan. Whether true or not, it was irrelevant and politically counterproductive.

Presidential aides tell us pardons to Poindexter and North might not be enough. What about Robert Secord and his partner, Albert Hakim, who may have profited by the deal? Even if a pardon to them could result in a deal recovering the $8 million in remaining arms sales profits that remain in Swiss bank accounts, Secord and Hakim are far apart from the case of Reagan's closest White House aides.

Another argument posed to us by White House aides: Michael K. Deaver and others caught in the conflict-of-interest quagmire also might have to be pardoned. That shows ignorance of the difference between a standard nonpolitical criminal proceeding and a witch hunt punishing bad White House decision-making.

Pardons might invite a charge now, just as seven months ago, that the president bought exculpatory testimony from his former aides with the coin of pardons. But if he fails to pardon, Reagan will add credence to the suspicion that he discards former servants with scarcely a backward glance once they become an embarrassment or lose their utility. Friends of Ronald Reagan are asking not whether he can afford the risks of pardons but the opprobrium of letting Ollie North and the admiral suffer through a criminal trial.