President Bush's abrupt turnaround in offering to hold a high-level diplomatic exchange with Iraq is designed to head off criticism at home and abroad that he has not yet tested every avenue for a peaceful settlement of the Persian Gulf crisis, administration officials said.

At the same time, while emphasizing that United Nations demands for Iraqi withdrawal from Kuwait are not negotiable, Bush offered Iraqi President Saddam Hussein a hint that future talks could center on other issues, such as Saddam's complaints against Kuwait. "Within the mandate" of the U.N. resolution, Bush said, "I will be prepared, and so will Secretary Baker, to discuss all aspects of the gulf crisis."

There are risks in Bush's gesture to Saddam. Despite his protests that it is not a concession, it could suggest to audiences at home and overseas that he is preparing to negotiate with Saddam, leading to cracks in alliance solidarity and uncertainty about U.S. resolve.

It would be even more serious if the initiative sparked new demands for a settlement that falls short of the U.N. resolutions. Officials said Bush faced a difficult job of explaining that Baker is neither delivering an ultimatum nor making a concession. "We don't want either one of those if we can help that," an administration policy-maker said.

As recently as this week, the White House rejected suggestions by Rep. Lee H. Hamilton (D-Ind.) and others that he send a special envoy to Saddam.

The officials said Bush now accepted the idea for several reasons. One is that he wanted to silence any complaints from Congress and allies that the United States was missing an opportunity for diplomacy between now and the Jan. 15 deadline set by the U.N. Security Council resolution adopted Thursday. The administration was unsettled by the criticism at congressional hearings chaired by Senate Armed Services chairman Sam Nunn (D-Ga.) this week.

At the same time, foreign ministers from the other four permanent members of the Security Council -- France, Britian, China and the Soviet Union who met privately with Baker in New York on Thursday night -- discussed the need for all the alliance partners to press Saddam to honor the U.N. resolutions, sources said. Although Baker did not tell the ministers in advance of Bush's planned announcement, the mission to Baghdad is very similar to what they were suggesting, the sources said.

Secondly, administration officials said, there have been recurrent reports from intelligence sources and from American friends in the gulf that Saddam believes Bush is not serious about the military threat, and that he can outwait the alliance. These reports suggest that the fear Saddam has instilled in his lieutenants dissuades them from giving him objective assessments and advice. Egyptian President Hosni Mubarak has told U.S. officials that Saddam personally assassinated subordinates during the Iran-Iraq war because of doubts about their loyalty.

"There is a history here of people around Saddam not feeling safe enough to tell him the truth," a senior official said. "This is part of the truth telling."

Judging the reasons behind Saddam's actions, and determining what will influence him, have been recurring problems for the administration. There is some evidence -- such as Saddam's efforts to split the alliance with hostage releases -- that the Iraqi president is feeling the pressure and trying to buy time to forestall military action. But contrary reports suggest that Saddam has concluded the alliance is just not serious about fighting him.

"I have not felt that he got the message," Bush said in his news conference yesterday. "I hope this will do it."

Since Iraqi forces invaded Kuwait last August, Saddam has made a series of overtures toward negotiations, all of which the United States has rejected. Among other things, Saddam has suggested peace talks that would encompass broader Middle East issues, in particular Israel's occupied territories and the future of the Palestinians. But Washington and its alliance partners have said Saddam's aggression against Kuwait cannot be rewarded by such negotiations.

Officials said Saddam's reaction to Bush's announcement may itself prove a useful barometer to his mindset in the period before the Jan. 15 deadline. If he takes up the offer, it may indicate he is interested in a peaceful settlement that could meet U.N. demands, they said. But if he rejects it out of hand, it will suggest continued intransigence. Under Bush's plan, before Baker could go to Baghdad, Saddam must first agree to send his foreign minister, Tariq Aziz, to Washington, where he would meet Baker, Bush and a group of allied ambassadors.

Aides said Bush first discussed the idea of sending an emissary to meet with Saddam on Wednesday with Baker and national security adviser Brent Scowcroft. They talked further on Thursday, and that evening Bush wrote out the language for the statement he delivered yesterday. Bush and Baker did not clue in the allies or Congress, however.

Officials said Bush also felt that it was important to inject a new diplomatic effort into the crisis now that the threat of military force was set by the U.N. resolution. Before the resolution, such an overture would have splintered the coalition, they said, but now may complement it.

"You need two tracks," a senior policy-maker explained. "If you only have a military approach, you lose political support. And if you only have a political approach, it will be feckless."

Administration officials acknowledge they have received no signal, public or private, suggesting a change in Saddam's stance. A number of emissaries from Europe, and Yevgeny Primakov, the special envoy of Soviet President Mikhail Gorbachev, have come back from Baghdad, reporting Saddam's intransigence.