The State Department's chief Kremlinologist, Marshall Shulman, plans to resign, the Chicago Sun-Times has learned.

Shulman wants to return to a teaching post at Columbia University. But he expects that Cyrus R. Vance, who resigned Monday as secretary of state, will try to talk him into staying on his job for a transitional period.

The department's chief Soviet theorist, whose title is special adviser to the secretary, often found himself opposing national security adviser Zbigniew Brezezinski in Brzezinski's foreign policy feuds with Vance, who resigned because of his opposition to the failed mission to rescue the 53 U.S. hostages in Iran.

Shulman said there is no connection between his planned resignation and Vance's protest.

"I've been thinking about returning to my university for some time," he said. "Now I may not be able to," referring to the pressure he may get from Vance.

Shulman would be the second senior department official to announce he is departing in the wake of Vance's resignation. Earlier this week, Deputy Secretary of State Warren M. Christopher said he plans to resign after making sure Vance's designated successor, Sen. Edmund S. Muskie (D-Maine), has a smooth transistion into office.

Christopher, like Shulman, is being pressured to stay on his job.