Two things might yet stop President Bush's momentum toward war with Iraq. One is a deathbed conversion by Saddam Hussein; the other is a last-minute defection by Tony Blair, the British prime minister who has been the president's key ally in the crusade against the Iraqi leader.
But neither is likely to happen.
Hussein has shown no sign of meeting the United Nations' demand for an immediate accounting of all past holdings of chemical and biological weapons. And U.S. officials argue that opposition to war by France, Russia and China is only stiffening the Iraqi president's resistance.
As for Blair, administration officials say they believe he is fully committed to their goal of disarming Iraq now -- and to joining Bush in waging war, if that is what it takes to get the job done.
As a result, despite mounting opposition from other governments, a U.S.-led war against Iraq appears ever more likely, no matter what happens at the U.N. Security Council in the days to come.
"There's a lot of momentum built up at this point," said James B. Steinberg, a national security aide to former President Clinton. "We now have more than 200,000 troops there, and they're not coming home without a victory."
Experts point to three reasons Bush hasn't diverged from his course. One is that he has long wanted to unseat Hussein -- a goal he proclaimed in his 2000 presidential campaign -- and believes he has reached a moment of opportunity that he dares not let slip away.
Another is that Bush and his aides believe that a war with Iraq is likely to be brief and relatively easy and that a resounding victory will force their critics into silence.
And the third is that after driving the confrontation this far, and sending tens of thousands of troops halfway around the world, Bush believes that backing off now would send a message to Iraq, North Korea and other adversaries that his threats should not be taken seriously.
"Our credibility is so deeply engaged ... the chances of not going to war are close to zero," Steinberg said. "Credibility is always the wrong reason to do something, but it is almost always a reason that presidents take important decisions."
Bush has served notice that he does not intend to be constrained even if the Security Council refuses to approve military action.
"When it comes to our security, if we need to act, we will act, and we really don't need United Nations approval to do so," he said in a news conference Thursday evening. "We really don't need anybody's permission."
"I've thought long and hard about the use of troops; I think about it all the time," he said. "It is my responsibility to commit the troops. I believe we'll prevail; I know we'll prevail. And out of that disarmament of Saddam will come a better world, particularly for the people who live in Iraq.... I've calculated the costs of inaction versus the cost of action, and I'm firmly convinced that, if we have to, we'll act in the name of peace and in the name of freedom."
Foreign policy experts outside the government agree that the alternatives to war are rapidly disappearing.
"I think it's pretty clear we're going to war," said Brent Scowcroft, who served as national security advisor to President George H.W. Bush, the current president's father.
"As every hour goes by, I think the chance of war is increasing," said Sen. Joseph R. Biden Jr. of Delaware, the senior Democrat on the Foreign Relations Committee. "I was hoping it wasn't, hoping there was a shot at doing this peacefully, but that looks slimmer and slimmer."
Biden agreed with Steinberg that the problem of credibility has become a real factor.
"If we leave, we lost," Biden said. "By the time we had 160,000 troops in the field, the option of keeping them there through August began to look pretty unrealistic."
Biden, who has been among the Senate's more hawkish Democrats on Iraq, said he will support the use of force to disarm Hussein but wishes the administration had found a way to keep more allies on board. "We're doing this at the highest cost we could have chosen," he warned.
Steinberg agreed, blaming Bush and French President Jacques Chirac for the outcome. If the U.S. and France had agreed on more specific interim goals for Iraq to meet last fall, he said, Hussein might conceivably have complied -- but even if he didn't, the United States would not be so divided from the other major world powers now.
"I wish we had another course available, but this is the course we're left with," he said.
"If the war goes well, it will be a major victory for Bush, of course, and catastrophic for France. But if the war goes badly, there will be recrimination across the board."
He warned that the administration has risked appearing overconfident.
"Normally, in a situation like this, you want to prepare the public for the possibility of a less-than-perfect outcome," he said.
"But in this case, any concession by the administration that there might be casualties or difficulties would only stoke the fires of opposition. That means they don't have much of a safety net if things go badly."