Judge Robert Bork's unexpected decision not to drop out in the face of certain Senate defeat is aimed not only at salvaging self-respect but is an effort -- viewed as misguided by his strongest supporters in the Reagan administration -- to prevent agonizing defeat from turning into prolonged retreat.

Even as Bork stunned Washington by not asking that his name be withdrawn, White House aides were suggesting that chief of staff Howard Baker this time wants prenomination consultation with the Senate to be more than the mere formality it was in Bork's case. What's more, names of surely confirmable but nonconservative nominees have surfaced: former HUD Secretary Carla Hills, newly installed CIA Director William Webster and even HUD Secretary Samuel Pierce.

Any of them would waltz through the Senate toward confirmation, but at a price. The liberal power structure will have established new guidelines for judicial confirmation, with the line drawn against Reaganization of the federal judiciary.

An angry President Reagan has vowed this cannot happen. He privately expresses determination not to send up any name pleasing to Joe Biden or Ted Kennedy. But the judge-selection process is less clear than it was last June when the president asserted with uncharacteristic finality that Bork was the only choice.

With Bork not withdrawing, naming his successor is delayed, possibly for weeks. That is why Bork's enthusiastic supporters in the Justice Department, from Attorney General Edwin Meese on down, privately prayed for the judge to withdraw. They then would have pressed for selection of a new nominee in just a few days and an accelerated confirmation.

So many Democratic senators had announced their positions, these officials argued, that a formal roll call vote would serve no purpose. Only Sen. Sam Nunn remained a mystery, and his popularity in Georgia puts him beyond electoral retribution. Besides, the withdraw-now argument went, the bitter debate could be personally humiliating to Bork.

Only Bork's adviser, lawyer Leonard Garment, argued for him to stay and fight a last-ditch struggle. But if Garment harbored illusions, the judge himself did not. When Senate Majority Leader Robert Byrd early last week finally announced his opposition, Bork picked up the telephone in a state of personal emotion to tell his wife, ''It's over.''

That is why his supporters in the administration wanted to turn the page and start on the new appointment. It would not be easy. Democratic operatives on Capitol Hill last week began preparing a case against two brilliant young judges on the 7th Circuit Court in Chicago whom they figure might be tapped: Richard A. Posner and Frank Easterbrook.

But while conservative, Posner and Easterbrook are considered judicial activists and have no more support at the Justice Department than at the White House. Strong sentiment at Justice was voiced for Gov. John Ashcroft of Missouri, a former state attorney general with a firm anti-abortion record, until an aide last Friday sent word to Washington that he is not interested.

Ashcroft would have fit the category of a conservative with excellent legal and political credentials. So does Judge Laurence Silberman, a colleague of Bork's on the D.C. Circuit Court who has wide governmental and political experience. A dark horse is still another member of the D.C. court: Judge Douglas A. Ginsburg, 41, a former Harvard law professor who is just finishing his first year on the appellate court.

The strategy at Justice was to fight off appeasement of the Democratic Senate with a moderate or a southern judge and hurry through the second nominee. Bork's undeniable request to give him his day in the Senate indefinitely delays the process.

The duration of that delay will tell whether Bork's determination helps or hurts the chances for a like-minded replacement. There is wide belief in the administration among all concerned that a public campaign in his behalf would come too late, energizing liberal pressure groups and perhaps pointing the White House toward selection of a neuter judge.

But nobody denies Bob Bork, victim of unprecedented character assassination, a Senate vote. His desire is strongly seconded by Secretary of Education William J. Bennett, who, when Republican senators seek his help campaigning on the hustings, will pay careful attention to which of them voted no on Bork. The notion that a negative vote can be costly might help prevent the defeat from turning into a rout.