President Bush, suddenly faced with increasing bipartisan opposition to his plan for an early military strike against Iraq, has scheduled a meeting with top congressional leaders of both parties for Thursday to discuss his Persian Gulf policy.

The move came as Senate Minority Leader Bob Dole, R-Kan., and Majority Leader George Mitchell, D-Maine, criticized Bush's plan to order an early attack if Iraq fails to abide by the Jan. 15 deadline for Iraqi withdrawal from Kuwait.It was not immediately clear whether Bush's tough new posture would prompt any serious move in Congress to force the president's hand - either by forbidding the use of military force or by specifically ordering an attack. Both houses will be in session from Thursday through Jan. 15.

Nevertheless, it was plain that top congressional leaders were extremely anxious about the reports of Bush's decision to move quickly once the U.N. deadline had passed.

Declaring that there is "still a lot of concern in the country about getting into a shooting war," Dole said the United States "should not be doing anything over there until we've pursued every other possibility" - including high-level talks between the two countries.

And Mitchell, who has repeatedly insisted that the U.S. Constitution requires the president to seek congressional approval before launching any offensive military action, said other senators also were apprehensive.

"I detect widespread and deep unease among members of the Senate about the manner in which the president appears so insistent and determined to use force as a first resort rather than a last resort," he said.

The meeting between Bush and congressional leaders was scheduled as both the United States and Iraq continued their apparent preparations for war, and - in a new twist - some Iraqi opposition groups in Beirut, Lebanon, announced plans to try to oust Iraqi dictator Saddam Hussein.

While the White House did not formally announce the Thursday leadership meeting, Dole disclosed in an interview that Bush's national security adviser, Brent Scowcroft, had told him that the president planned to schedule two meetings with congressional leaders for that date.

Bush plans to meet first with Mitchell, Dole, House Majority Leader Dick Gephardt, D-Mo., and House Minority Leader Bob Michel, R-Ill., and then hold a second session to include some 20 others, among them the chairmen of the armed services and foreign affairs committees.

Scowcroft, Defense Secretary Dick Cheney, Secretary of State James Baker and other senior officials are expected to attend the meetings.

The growing sentiment in the Democratic-controlled Congress for greater efforts to seek a peaceful settlement of the Persian Gulf crisis drew a lukewarm response Friday from one of the key Democrats, Rep. Les Aspin, D-Wis., chairman of the House Armed Services Committee.

Aspin issued a report arguing that almost any peaceful solution is likely to be perceived by Arabs as a victory for Saddam Hussein.

"Almost any outcome that includes Saddam's survival is likely to be trumpeted (in the Arab world) as a great victory for Saddam," he said.

Even so, Aspin stopped short of calling for the early use of military force to make sure that Saddam does not survive.

Dole said he would still like to see the United States try to arrange for Baker to travel to Baghdad, Iraq, to meet with Saddam, and for Iraqi Foreign Minister Tarik Aziz to come to Washington and meet with Bush before Jan. 15.

So far, the United States and Iraq have been unable to agree on dates for reciprocal talks on the crisis. A planned visit by Aziz to Washington was canceled after the Bush administration rejected the Jan. 12 date that Iraq had proposed for a meeting between Baker and Saddam.

Dole said he feels so strongly about the issue that he telephoned Iraq's ambassador to the United States, Mohammed Mashat, in Baghdad to urge that the Iraqis try to agree on a date before Congress returns to Washington Wednesday.