WASHINGTON – Hundreds of thousands of anti-war protesters will descend on the nation’s capital this weekend, demanding that Congress and President Bush withdraw American soldiers from Iraq.

Yet as Washington girded for three days of demonstrations, President Bush promised yesterday to remain firm in his support of the war effort.

In remarks delivered at the Pentagon, the president said Americans who want to withdraw troops from Iraq to escape violence have “good intentions, but their position is wrong.”

“To leave Iraq now,” Mr. Bush said, “would be to repeat the costly mistakes of the past that led to the terrorist attacks of September the 11th, 2001.”

“The battle lines are drawn, and there is no middle ground,” the president said. “Either we defeat the terrorists and help the Iraqis build a working democracy, or the terrorists will impose their dark ideology on the Iraqi people and make that country a source of terror and instability to come for decades.”

This weekend’s “mobilization” against the war in Iraq is being organized by a New York-based anti-war coalition, United for Peace and Justice, which has staged similar gatherings in the past. UFPJ will be joined by a constellation of left-leaning anti-war organizations from across the country, ranging from ANSWER to Code Pink to the U.S. Campaign to End the Israeli Occupation.

Unofficial anti-Israel events are scheduled to begin this evening, but the major festivities will kick off with a rally at the Ellipse tomorrow morning. From there, demonstrators are scheduled to parade around Washington, past the White House. Tomorrow evening brings an “Operation Ceasefire” concert, and Sunday’s activities will include training in “non-violent resistance” for those who plan to participate in Monday’s act of “massive non-violent direct action at the White House,” according to the weekend’s schedule.

“There’s a lot of momentum and excitement about this mobilization,” a spokesman for UFPJ, William Dobbs, said yesterday. Mr. Dobbs cited a growing sense of public discontent with the Iraq war over the summer – fueled by plummeting poll numbers, the formation of a congressional “Out of Iraq Caucus,” the Downing Street memo, and “14 Marines from the same town in Ohio killed in the same day”- as “the reason why there’s excitement and momentum.”

“The swirl of events – all those developments over the summer – have created a surge in the number of people who want to stop this war,” Mr. Dobbs said. The mobilization will also address Hurricane Katrina, he said, adding that the natural disaster in creased the sense of urgency felt by those who believe the war to be misguided.

“This senseless war is continuing to cost lives, now over 1,900, and huge amounts of money, while emergency preparedness and relief efforts are under-funded,” he said.

While Mr. Dobbs said he expected “hundreds of thousands” to join in demanding that Congress and the president “bring the troops home now,” his will not be the only activists demonstrating here this weekend.

The organizer of a pro-troops counter-protest, Kristinn Taylor, said yesterday that it appeared more likely that only 100,000 would attend the UFJP mobilization, and that the protests should not be taken as a sign of massive discontent with the war effort.

“We’re a country of 300 million people,” Mr. Taylor said. “They’re only going to draw 100,000. That’s not very impressive … 100,000 people go to football games every weekend, and they pay more money to do it.”

The UFJP demonstration, Mr. Taylor said, represented “the usual crowd,” which, he added, would succeed only in encouraging the enemy. Mr. Taylor’s counter-protest, he explained, was intended to signal that Americans “are not weakening in our resolve, that we’re going to fight this to the finish, and the terrorists will lose.”