Senate leaders yesterday took steps toward issuing a subpoena for Soviet sailor Miroslav Medvid, who twice jumped into the Mississippi River last month only to be returned to his ship, to give him another opportunity to defect.

The subpoena would require the young seaman to appear before a Senate panel or a group of senators before his ship leaves U.S. waters, which it is scheduled to do Friday or Saturday. A federal judge in New Orleans last night refused to prevent the Soviet grain freighter Marshal Konev from departing on schedule.

"We want to use the legitimate authority that we have to give this fellow one more chance to walk out of the gulag," George Dunlop, an aide to Sen. Jesse Helms (R-N.C.), said.

The Senate Agriculture Committee, which Helms chairs, voted to issue the subpoena yesterday, but Majority Leader Robert J. Dole (R-Kan.) later said the subpoena should be issued by the full Senate. A Dole aide said a resolution for a subpoena would require unanimous consent.

Meanwhile yesterday, a Romanian merchant seaman jumped ship in Jacksonville, Fla., and was reportedly seeking political asylum, sources told the Associated Press. U.S. officials were reported to be interviewing the man, tentatively identified as Stefan Vranea.

The Medvid case began Oct. 24 when the 22-year-old seaman jumped from the Marshal Konev into the Mississippi near New Orleans. Medvid, who speaks no English, was returned to the ship -- struggling and complaining -- though an interpreter later said he had explicitly requested political asylum.

Immigration and Naturalization Service commissioner Alan C. Nelson has acknowledged that the officials who decided to have Medvid taken back to the freighter failed to follow proper procedures in their initial handling of the sailor.

Once U.S. officials learned of the mistake, Nelson said, they had Medvid taken off the ship, had him examined by physicians and psychiatrists over a period of four days and asked him if he wished to defect. But Medvid said he wanted to return to the Soviet Union, Nelson said, and was again returned to his ship.

Since then, the Medvid case has been at the center of three court proceedings, a Senate hearing and protests from Ukrainian and other organizations.

In a letter sent to other Senate Agriculture Committee members Tuesday night, Helms wrote that Medvid had suffered "physical brutalization" by Soviet officials and "has as yet been unable to realize his original intent to gain freedom."

State Department spokesman Charles Redman yesterday described reports that Medvid might have "slashed his wrists" after being returned to the ship early on Oct. 25 as "probably not the most accurate characterization."

On Tuesday, William M. Woessner, acting assistant secretary for European affairs, told a Senate subcommittee that Soviet crew members had said Medvid cut his wrists.

However, when a U.S. doctor boarded the ship and examined Medvid, he found "only a minor injury to his left arm," Redman said. He described the wound as a superficial 2 1/2-inch laceration.

Redman added that when Medvid was asked how he got the cut, he replied that he had been unconscious for a time after jumping into the water and could not remember.

Redman said the possibility that Medvid might have attempted suicide was a factor in the questions that U.S. officials asked during subsequent interviews and was a reason why the United States insisted that Medvid undergo a series of tests and be interviewed by a psychiatrist.

In New Orleans last night, District Court Judge Martin L.C. Feldman refused to issue a temporary restraining order preventing the Marshal Konev from leaving U.S. waters and requiring the government to produce Medvid.

Feldman said the sailor "probably did initially desire to defect" but "there's no doubt" the State Department decided he later changed his mind. Feldman also said that, given the thoroughness of the department's interviews with Medvid and the rulings of other courts in the matter, he had no reason and no legal authority to hold the ship.

In court proceedings, Feldman was told that Medvid had to be tackled, handcuffed and carried kicking and screaming back to his ship early on Oct. 25.

Michael Flad, the ship's U.S. agent, said that when the small launch carrying Medvid pulled alongside the freighter, the sailor dove into the river a second time. The launch pursued him, Flad said, and Medvid swam under a life ring thrown to him. He scrambled ashore about the time the launch reached the bank, Flad said.

"The second mate ran over and tackled him," he said. "I arrived to help. The man was kicking and punching . . . . "

Eventually, Flad said, Medvid was subdued and handcuffed. As the sailor lay on the boulders along the bank, Flad said, he "started banging his head against the rocks, and we moved him so he couldn't hurt himself."