President Bush wants to wait to ask Congress for authorization to use military force in the Persian Gulf until after the U.N. Security Council considers a proposed resolution supporting the use of force against Iraq, according to Sen. Richard G. Lugar (R-Ind.).

The president told Lugar in a phone call last Thursday that he hoped a U.N. vote "would focus the issue for Congress" because he and his aides felt they "did not have the votes" to pass such a resolution, the senator said yesterday in a breakfast meeting with reporters.

Bush indicated, Lugar said, that "if the U.N. doesn't work out . . . this would not be the time to make a pass at Congress."

Meanwhile, two Senate committees preparing to hold hearings on the gulf crisis in the coming weeks have had problems lining up key Bush administration officials as witnesses. The hearings were scheduled after congressmen began complaining publicly that Bush had not consulted Congress before deploying additional troops to the gulf, prompting some members to call for a special session to discuss the situation.

In a related development, 45 congressmen filed suit in federal court in Washington yesterday, challenging Bush's constitutional authority to order U.S. forces to attack Iraqi troops without a formal congressional declaration of war. Led by Rep. Ronald V. Dellums, (D-Calif.), the lawmakers seek to bar the president from starting "an offensive war" on his own. Bush and his advisers have said frequently since Iraq invaded Kuwait on Aug. 2 that he has authority to do so.

The suit seeks an injunction barring the president from launching an attack against Iraq without congressional approval and argues that Bush is in danger of violating the Constitution, which delegates to Congress the power to declare war.

"Throughout the Cold War era too many presidents have taken this nation into presidential wars without the full, informed consent of Congress and the American people," Dellums said in a statement. "My colleagues and I are determined not to let history repeat itself."

No hearing date has been set for the case, which has been assigned to U.S. District Judge Harold H. Greene.

But the first of two sets of Senate hearings is scheduled to start next week. The Armed Services panel plans to begin three days of hearings on Tuesday, hoping to get Defense Secretary Richard B. Cheney to appear before he travels out of Washington the following week, according to sources.

In a letter inviting Cheney to testify, committee Chairman Sam Nunn (D-Ga.) said the panel wanted to review the administration's policy and "the rationale for recent changes," a reference to the decision earlier this month to deploy an additional 200,000 U.S. troops to the gulf and put off a rotation of the forces already there.

As of yesterday, however, Cheney and Gen. Colin L. Powell, chairman of the Joint Chiefs of Staff, had yet to agree to a time to testify, sources said. A spokesman for Cheney said yesterday that Dec. 3 was the first date he could appear, "but we are working on it."

Although the committee likes to open such hearings with testimony from senior administration officials, the session now is scheduled to begin with James R. Schlesinger, a former defense secretary. The panel has also requested a closed intelligence update, but that session has yet to be confirmed, sources said.

The committee has lined up former secretary of state Henry A. Kissinger, former Joint Chiefs of Staff chairmen David C. Jones and William J. Crowe Jr. and other witnesses to explore such issues as Iraq's military threat, the Iraqi economy and the effect of the economic sanctions against Iraq.

After some scheduling problems of its own, the Senate Foreign Relations Committee yesterday finally won a commitment from Secretary of State James A. Baker III to appear on Dec. 5 as part of that panel's two days of hearings. Baker plans to break off from Bush's trip to Latin America to return to Washington for his appearance.

The Foreign Relations Committee will focus on U.S. policy along with regional diplomatic and political issues, according to committee sources. In some cases it is inviting some of the same potential witnesses sought by the Armed Services Committee.

Lugar said yesterday that he believed the hearings might be helpful but that for members of Congress they were "an easy way to punt" rather than debate and vote during a special session of Congress on whether to authorize the president to use force in the gulf crisis.

Sen. John W. Warner (Va.), ranking Republican on the Armed Services panel, said yesterday the sessions would also give senators who have been complaining about the administration's approach a chance to discuss how they would do handle things. "Congressmen are looking for half the authority to establish policy," Warner said. "They should also accept commensurate responsibility for decision-making."

In a related event, congressional leaders took off yesterday from Andrews Air Force Base to join Bush in his Thanksgiving Day visit to U.S. troops in Saudi Arabia.

Bush issued a surprise invitation last Thursday to the Senate majority and minority leaders, George J. Mitchell (D-Maine) and Robert J. Dole (R-Kan.). Two House leaders -- Speaker Thomas S. Foley (D-Wash.) and Minority Leader Robert H. Michel (R-Ill.) -- were invited later by Brent Scowcroft, Bush's national security adviser.

"It is one of those invitations that is tough to refuse," an aide to one of the leaders said yesterday. For all four it meant a change in holiday plans, and for Democrats Mitchell and Foley it carried the added potential problem of indicating support for some of Bush's statements with which they have disagreed.

"If you don't go," the aide said, "it gives a signal to Iraq and others that you don't want to give."

Staff writer Tracy Thompson contributed to this report.