Yale law professor Eugene V. Rostow, a longtime Democrat who served in the Johnson administration but whose hawkish views on defense and foreign policy turned him into a supporter of President Reagan, has suddenly emerged as a possible candidate to run the U.S. Arms Control and Disarmament Agency (ACDA) under Reagan.

Several administration officials and sources close to Rostow confirmed yesterday that the 67-year-old former undersecretary of state in the Johnson years had been approached about the ACDA job.

The ACDA directorship is, potentially at least, a key post because it involves shaping U.S. policy toward the Soviet Union in the crucial and controversial area of nuclear arms control and limitations.

The leading candidate for the job was widely believed to be retired Army Lt. Gen. Edward L. Rowny, 63, who had represented the Joint Chiefs of Staff in the U.S.-Soviet strategic arms limitation talks (SALT) during the Carter administration and then resigned because he objected to some portions of the pact signed by Carter.

Rowny still has important backers, reportedly including Secretary of State Alexander M. Haig Jr. and some conservatives in Congress, and no final White House decision has been made.

Yesterday, however, senior administration officials said privately that, without demeaning Rowny, several people feel Rostow would make an excellent negotiator and articulator in the arms control area. Some officials said, however, that Rostow might turn down any other personal of health reasons.

On Capitol Hill, sources let it be known that, after a luncheon meeting with White House national security adviser Richard V. Allen, Sen. Jesse Helms (R-N.C.) sent word to the White House that, even though he has high regard for Rostow's reputation, he would put a hold on the nomination if it came before the Senate.

Helms has consistently backed Rowly, and sources said some other senators share that view.

Several sources say the two-month search for an ADCA head reflects an administration still deeply divided and battling privately about some basic decisions dealing with national security.

These sources agree that support for Rowny, even among conservatives, began to sag as the decision was delayed. Moderates critical of Rowny question whether he will be a real advocate of arms control, and conservatives are concerned that he might be too passive a bureaucrat, unwilling to challange Haig, if necessary.

In a related matter, the administration is expected to ask Moscow to postpone a meeting of the U.S.-Soviet Standing Consultative Committee that was to convene in Geneva next Wednesday. In that committee, both nations usually discuss questions of compliance with the previous SALT agreements.

The postponement may appear a small diversion, but its impact is important and several administration officials think it was handled poorly by the State Department and the White House's fledgling national security decision-making apparatus.

In effect, some officials argue, the decision not to go to Geneva was informal and not subject to broad review.

Rather, they believe, it came after recommendations, Haig and some of his subordinates, followed by press leaks that the administration was moving in that direction, then a decision not to embarrass Haig by deciding to go.

Administration sources confirmed that the Joint Chiefs of Staff and acting heads of the arms control agency felt that the postponement was not a good idea as did adviser Allen, although he reportedly also felt there were resonable arguments for a delay.

The State Department view, apparenty supported by Defense Secretary Caspar W. Weinberger, was that the United States needed more time to think about its position on SALT.

In addition, there was concern that a compilation of alleged Soviet SALT violations, prepared by some ACDA officials known for their zeal on the issue, should be more carefully prepared before presentation to the Soviets.

On the other hand, the joint chiefs argued that SCC meetings are an extremely valuable forum in which the United States can discuss SALT compliance with Moscow and U.S. and Soviet military officers can meet face to face.

ACDA officials and several State career officials argued that postponing a meeting that had never been postponed previously could result in unnecessary diplomatic costs with Moscow and U.S. allies interested in continuation of the SALT process. SCC meetings have been held semiannually for years.

These officials argued that the United States could have gone to Geneva and taken any number of positions that made it clear the new administration was not signaling acceptance of SALT or Soviet behavior. That would at least have left the forum intact, they say.

Although some State Department officials argue that the postponement is merely to allow the administration more time to work out its position, and not a signal to Moscow, others say the Soviets will not see it that way.

As of yesterday, sources said that while the administration was likely to ask for postponement, no decision had been made. With the meeting only a week away, it was not clear whether the Soviets or U.S. allies had been officially informed.

There was also no indication of whether Moscow would agree to a rescheduled meeting in a month or two. An interagency meeting, chaired by the Senate Department, is reportedly set Friday to review the U.S. approach to SCC meetings.

Among those who feel the United States should not tamper with the SCC schedule and who worry about sending an incorrect signal to Moscow are officials who believe that the Soviets can expand their nuclear forces more quickly than can this country and that the United States should do nothing haphazard that suggests breaking off the SALT process.