A federal judge yesterday told presidential hopeful Marion G. (Pat) Robertson that he would have to spend next March 8 -- a day known to the political world as "Super Tuesday" -- in a D.C. courtroom unless he can settle his libel suit against former U.S. representative Paul N. (Pete) McCloskey Jr. (R-Calif.).

U.S. District Court Judge Joyce Hens Green, urging the parties to resolve their dispute without a trial, tentatively set March 8 as the first day of proceedings in a trial that would probably run 10 days or more and would likely feature witnesses challenging the veracity of both Robertson and McCloskey.

That could be a serious problem for Robertson's political hopes if he were a serious challenger after the Super Tuesday primaries in 20 states, most of them in the South. While his competitors for the Republican nomination would be out campaigning, he would be tied to the courtroom defending his integrity in a public proceeding.

Green's announcement may increase the chances that Robertson and McCloskey will reach an out-of-court settlement. Participants on both sides said little progress was made toward a settlement in yesterday's pretrial conference, but lawyers are to meet again today to seek a resolution both sides can accept.

Robertson and McCloskey served together briefly as Marine lieutenants during the Korean war. McCloskey has charged that Robertson, the son of a U.S. senator, used his father's political clout to be transferred off a troop ship carrying his Marine unit to Korea in 1950. Robertson sued for libel, asking for a retraction and $35 million in damages.

In depositions, Robertson said he was advised to file the lawsuit by Paul Weyrich, a Washington conservative leader who has helped shape Robertson's political plans. Robertson also said he felt a need to bring the suit to preserve his late father's reputation.

But in recent weeks Robertson has indicated to political backers that the suit could make his campaign more difficult, particularly if it comes to trial during the 1988 primaries. He told Time magazine last week that he thinks "it was a bad idea" to bring the suit. Moreover, Robertson has faced criticism from some of his fellow evangelical Christians, who believe it violates biblical teachings to file a lawsuit.

According to depositions so far, a trial would produce some witnesses who support Robertson's position -- that he never used political clout to avoid combat duty -- and others who agree with McCloskey that Robertson received parental help and is being untruthful about it.

The proceedings have established that Robertson was taken off the troop ship carrying him and McCloskey to Korea, but there is no direct evidence proving that his father arranged that. Robertson eventually went to Korea but did not see combat.

Robertson last week suggested that McCloskey's legal expenses in the suit are being paid by Arab interests; Robertson said he had no proof, however. McCloskey said this suggestion is false.