A seemingly minor disagreement over the scheduling of Senate hearing witnesses may begin a classic struggle between Congress and the presidency over Persian Gulf war policy, with George Bush and Sam Nunn engaging each other in a clash that could be repeated in the 1992 presidential election.

Defense Secretary Dick Cheney and Gen. Colin Powell, joint chiefs chairman, had agreed to appear before Chairman Nunn's Senate Armed Services Committee Nov. 26 on the opening day of hearings into Bush's policy. President Bush quietly intervened, ordering them not to appear, because he wanted Secretary of State James Baker to be the first official to set forth administration policy. Baker would appear not before Nunn's Armed Services panel but before the Senate Foreign Relations Committee.

That dispute follows wrangling behind closed doors at the White House between Bush and Nunn over the president's complaint that Saddam Hussein's controlled press in Baghdad was playing up criticism leveled by another Democrat, Sen. Daniel Patrick Moynihan of New York. Nunn was incensed.

Behind such sparring are Nunn's objections to plunging the United States into war with Iraq before Bush's initial strategy of sanctions and isolation has provably failed. The Georgian has built a reputation as the successor to Richard Russell and Scoop Jackson, who were keepers of the pro-defense Democratic tradition. This is no Ramsey Clark firing popguns from the left.

Nunn, surprised by the unusual refusal to permit Cheney and Powell to testify Nov. 26 as scheduled, postponed his hearings one day to Nov. 27. But Baker will not be back from his worldwide travels to appear before Foreign Relations by then. Nunn's lead witness instead will be former Republican defense secretary James Schlesinger, who has been critical of Bush's policy.

For Bush to insist on Sen. Claiborne Pell's Foreign Relations Committee getting the first word on Gulf policy runs counter to political reality. Nunn, not Pell, is the accepted Democratic leader on war and peace and complex related matters: strategy, use of force and the command structure. Barring Cheney's testimony to Armed Services may reflect White House concern over 1992 and the prospect of Nunn as the nominee.

It also may have something to do with the president's meeting with congressional leaders Nov. 14. Led by Nunn, Democratic critics warned Bush that if he really planned to attack Iraqi forces in Kuwait, he would have to explain that the initial strategy -- sanctions -- has failed and tell just how he knows it has failed.

Nunn sparred with the president at that meeting when Bush showed how Baghdad newspapers had played up Moynihan's sharp criticism of Bush's policy. A senator present told us that Nunn asked Bush if he had also studied Iraqi press reaction to Gen. Michael Dugan's call for surgical air strikes that might "take out" Saddam (an indiscretion that quickly led to Dugan's ouster as Air Force chief of staff).

Bush's implication that Moynihan was a pawn in the hands of Saddam's propaganda machine infuriated Nunn and Democratic colleagues. They saw it as the White House signaling what would follow if Armed Services now builds a strong anti-war consensus that handcuffs Bush.

Nunn's basic dispute with the Bush policy is that under the original plan, restoration of Kuwait independence was to be achieved by political means. But now Bush is looking at a military option. According to military sources, the U.S. commander in the Gulf -- Gen. Norman Schwartzkopf -- told Nunn he never had been ordered to prepare for offensive action.

Risking American lives to safeguard Saudi Arabia with its vast oil reserves is vital to the U.S. national interest, Nunn contends. But while restoring Kuwait to independence is the right objective for the United States, it is not "vital" to U.S. national security. Thus, he opposes sacrificing American lives in a war of liberation to free Kuwait under present circumstances.

In Nunn's view, the new U.S. military buildup is a dangerous incitement to conflict because it rules out troop rotation, thereby pressuring an end to the conflict by action. The senator is saying that the more American forces there are on the ground in Saudi Arabia, the less patience there will be in Washington and all over the country.

Nunn worries that even a relatively quick military victory would not solve but would compound long-range problems. He tells intimates that the proper question is not whether war is justified but whether it is wise. This great debate between Congress and the president cannot be overridden by pulling Pentagon witnesses off hearings and claiming Democratic senators are feeding the Baghdad propaganda mill.