President Bush tried to mollify members of Congress angered over the troop buildup in the Persian Gulf, but some members planned to try to block any offensive moves, while the latest round of shuttle diplomacy went nowhere.

Bush assured congressional leaders Wednesday the U.S. military position in Saudi Arabia was defensive and most heeded his call, ruling out an immediate special session of Congress.But liberal members were not convinced and, in what is believed to be an unprecedented step, 33 Democratic members of the House of Representatives, led by Rep. Ronald Dellums, D-Calif., say they will seek a federal court order to prevent Bush from taking offensive military action without consulting Congress first.

After a briefing by Secretary of State James Baker, Sen. Edward Kennedy, D-Mass., emerged to say he was "increasingly concerned that the president is preparing to take this country unilaterally into war in the Persian Gulf, without the approval of Congress and without the support of the American people."

Kennedy, when asked if a declaration of war would pass in Congress, replied, "Not after the hearings and not after a week's debate. There's not the slightest question in my mind. It would not, and I don't believe it's justified under the circumstances."

The lawsuit, set to be filed Thursday, challenges the president on constitutional, not political grounds. The plaintiffs contend that only Congress, not the president, can declare war.

At a White House meeting Wednesday, House Speaker Thomas Foley and others asked Bush to be patient. Foley suggested that the economic embargo may take as much as 18 months longer to force Iraq to withdraw from Kuwait, according to a senior congressional source.