On Tuesday afternoon, when some leading House Democrats drafting a resolution on the Persian Gulf crisis had trouble getting started, Majority Leader Richard A. Gephardt (D-Mo.) reached into his pocket.

He pulled out a draft that he said originated with Sen. Sam Nunn (D-Ga.), chairman of the Senate Armed Services Committee, among others. It remains the basic language for the House Democrats because, as one source present at the meeting said, "If something comes over {from the Senate} with a Nunn stamp, it takes on an aura."

Until the Nunn version appeared, "we were trying to figure out how to authorize force, but put constraints on the president in order to deter him. With Nunn's language, we were ready to say 'no force now,' and confront him."

Nunn, who took a major stand last November in opposition to President Bush's doubling of U.S. troops in Saudi Arabia, has now become a central figure in the congressional move to continue economic sanctions and, for the time being, deny Bush authority to use those forces to drive Iraq out of Kuwait.

For the Democrats, the Persian Gulf debate on Capitol Hill may turn out to be a political litmus test for the entire party, not just Nunn, on fundamental issues of war and peace that have plagued it since the Vietnam War.

One of the central ironies of the debate is that Democrats have taken the lead on both sides of the gulf question. The president's key congressional allies and his key adversaries are almost all Democrats.

In one respect, the gulf debate has united previously disparate groups within the Democratic Party: Sen. David L. Boren (D-Okla.), chairman of the Senate Select Intelligence Committee, and Nunn -- both moderates on national security issues -- suddenly find themselves in harmony with Rep. Ronald V. Dellums (D-Calif.) and Sen. Tom Harkin (D-Iowa), longtime liberals. All are working cooperatively with the Democratic leadership in both chambers.

At the same time, however, fissures have emerged on the Democratic side, fissures that observers believed yesterday could allow the administration position to prevail when the votes are taken Saturday.

One of the Democratic divides was rooted in the expected defection of Southern conservatives, who have dissented from the liberal wing of their party on many foreign policy and military spending issues since the Democrats moved to the left in 1960s.

Another involved the decision of a number of pro-Israeli Democrats, led by Rep. Stephen J. Solarz (N.Y.), to join the administration along with Rep. Dante B. Fascell (Fla.), the chairman of the House Foreign Affairs Committee. In the process, the usually dovish Foreign Affairs Committee has become a bastion of support for the Bush administration.

On the other side, Senate Majority Leader George J. Mitchell (D-Maine) and House Speaker Thomas S. Foley (D-Wash.) have taken tougher positions in the debate than they have in the past.

Foley and Mitchell have "shown fire for the first time," one Republican member of the House leadership said yesterday.

Mitchell set up a special group to handle preparation for the debate that included not only Nunn and Boren, but also Sens. Carl Levin (D-Mich.) and Bob Graham (D-Fla.). Both have large constituencies that support Israel. Whether or not by design, in making them part of this coordinating group, Mitchell may limit the defection of pro-Israel legislators that has taken place in the House.

Foley has gained new respect from Democratic liberals, who believed until yesterday that the speaker was more interested in keeping in step with Bush than he was in reflecting his own deep concern about war.

"Foley's passionate plea against the war was a surprise to liberals because none of them was certain before this morning that he really felt that way," a House source said.

Fascell, in turn, turned out to be a pivotal figure for the White House. Since August, he has hoped that a way would be found keep the Democratic Congress and the Republican president together in dealing with Iraqi President Saddam Hussein.

Despite his tenure and his committee chairmanship, Fascell is not a major player in the House hierarchy. Although he has established a direct connection with Bush, White House operatives are nervous about whether he accurately reflects what is going on in the House.

He also has had his differences with the White House. He had urged Bush to seek a resolution from Congress authorizing the use of force once support had been gained from the United Nations. The president turned him down because aides feared Fascell, along with House Armed Services Committee Chairman Les Aspin (D-Wis.), could not deliver the strong favorable vote they promised.

Earlier this week, Fascell, who had already discussed resolution language with the White House, was invited to participate in the Democratic leadership group headed by Gephardt. When it appeared that Nunn-type language -- withholding permission for the use of force to give sanctions more time to work -- was going to be adopted, Fascell appeared at the White House along with Solarz and other Democrats to work out a resolution satisfactory to Bush.

"As chairman," Fascell said yesterday, "I was involved in looking at all positions and helping both sides so there would be clean votes on the issue."

Fascell "felt it was the right thing to move in {Bush's} direction," Rep. Jerry Lewis (Calif.), chairman of the House Republican Conference, said yesterday. "His move made other Foreign Affairs Committee members more comfortable in supporting the president."

On the other hand, the White House appears unsuccessful so far in finding a Democratic senator who can perform the function provided by Fascell.

As he waited on the steps of the Capitol for a car to take him to a White House meeting, administration supporter Sen. Ted Stevens (R-Alaska), said he was worried about the way things were going. "It looks like we're missing a Henry Jackson," he said, referring to the late Democratic senator from Washington state who often sided with Republican presidents on national security issues and brought other Democrats with him.

On the Republican side of the aisle, very few defections from the administration are expected in the House or Senate.

The Persian Gulf debate is is likely to help shape the images of the two parties and could be important in determining the 1992 prospects of Bush, Nunn and Gephardt.

For two decades, the dovish tilt of the Democratic Party has been viewed in a number of quarters as a liability in presidential contests, but the Persian Gulf conflict is different.

Rep. Mel Levine (D-Calif.) said that he sees in the conflict a much stronger "analogy to the 1930s," when the issue was the growth of European fascism, than to the 1960s, when the issue was communism and Vietnam.