WASHINGTON - Days from announcing an overhaul of Iraq strategy, President Bush on Friday encountered a wall of criticism of the US troop escalation that is expected to be the centerpiece of his new war plan.

Bush also reshuffled his war commanders, installing a new team to support the policies he will announce next week. Democrats and Republicans alike took aim at the expected increase in US forces.

"It has to be significant and sustained. Otherwise do not do it," said Sen. John McCain, a Republican presidential hopeful and Vietnam veteran who has been advocating a troop increase.

Those for going in the opposite direction spoke out, too.

"We are well past the point of more troops for Iraq," new House Speaker Nancy Pelosi, D-Calif., and Senate Majority Leader Harry Reid, D-Nev., wrote in a letter to Bush a day after their party took the reins on Capitol Hill. Instead, Pelosi and Reid urged Bush to begin pulling troops out in four to six months.

The criticism underscored that Bush, preparing his new policy for an increasingly unpopular and costly war, will face a Congress that is not only controlled by Democrats who could challenge him at any turn but also populated with Republicans looking toward the congressional and presidential elections of 2008.

The president spent much of the day in last-minute consultations with members of Congress from both parties, by all accounts soliciting their input while giving few hints of his own plans. But doubts about dispatching more soldiers to Iraq -- which Democratic Sen. Ben Nelson called "the elephant in the room" at the White House -- were expressed to the president's face and before various audiences around Washington.

Rep. Heather Wilson, R-N.M., an Air Force veteran and member of the House Intelligence Committee who had just returned from Iraq, lambasted Bush's war leadership as lacking "a clarity of mission."

She spoke at a news conference against sending more Americans, saying the U.S. should be focused only on hunting for al-Qaida terrorists and ensuring Iraq does not become a source of regional instability.

"We're talking about goals in lofty terms that are not vital American national interests," she said.

Bush, meanwhile, announced more changes in his team of military and diplomatic advisers.

He said Gen. John Abizaid, the top US commander overseeing the theater that includes Iraq, will be succeeded by Adm. William Fallon, now Abizaid's counterpart in the Pacific. Army Lt. Gen. David Petraeus is the president's choice to be the new chief commander in Iraq, replacing Gen. George Casey. The nominations must be approved by the Senate.

Petraeus led the 101st Airborne Division during the 2003 Iraq invasion and later headed the effort to train Iraqi security forces.

Both Abizaid and Casey already had been expected to rotate out of their jobs. Both also had publicly expressed skepticism about a troop increase, and when Bush began devising a new Iraq plan their timetable appeared to move up.

Also, Ryan Crocker, a veteran American diplomat who is now U.S. envoy to Pakistan, was expected to replace Zalmay Khalilzad as US ambassador to Iraq. Bush nominated Khalilzad, a subject of criticism in Iraq as favoring his fellow Sunni Muslims, to become the US ambassador to the United Nations.

In a White House that prides itself on discipline, there was much confusion about the personnel changes. There was a torrent of news leaks, unsuccessful efforts by the White House to control the flow of information and messy shifts in how the announcements would be made.

The president's talks Friday with several groups of lawmakers included moderate Democrats and loyalist Republicans but also some of the president's biggest critics, such as Democratic Sens. Hillary Rodham Clinton and Barack Obama.

"He did say he has not made up his mind yet," said Rep. Chris Carney, a freshman Democrat from Pennsylvania who is in the Navy Reserve and served as a Pentagon intelligence analyst.

Republican Sen. Norm Coleman, part of a later meeting with over a dozen senators of both parties, said the skepticism about whether a burst of troops could achieve anything was nearly universal.

"I don't think there was a sense that case had been made," said Coleman, from Minnesota.

Several senators said Bush promised an increase would be done only in concert with greater efforts by the Iraqi government, which has failed to rein in the Shiite militias and to supply the promised amount of Iraqi forces to work alongside Americans.

Nelson, who said he walked away with no doubt Bush is planning to boost troops, said the president suggested there would be "the expectation of the Iraqis carrying out their part of the deal or else." But, said the Nebraska Democrat, the president did not define the consequences.

Iraqi Prime Minister Nouri al-Maliki, set to unveil his own revamped strategy within days, is himself uneasy about more American troops, preferring that the US presence be pulled back to Baghdad's outskirts.

During a nearly two-hour discussion Thursday, Bush told al-Maliki he was ready to send additional U.S. forces. But the Iraqi leader replied "he would have to talk that over with his senior military officers to see if they were needed," Sami al-Askari, an al-Maliki political adviser, told The Associated Press.

Sen. Joe Lieberman, meanwhile, agreed with McCain that a small, temporary force boost would not be enough. Neither of the senators, appearing together at the conservative American Enterprise Institute, would put a precise number on how many more troops might be necessary.

However, they said that -- at minimum -- it should be another three to five brigades for Baghdad, where Shiite militias are terrorizing the minority Sunni population, and one brigade for western Anbar Province, the center of the mostly Sunni anti-American insurgency. With about 3,500 troops in each brigade, that would total 14,000 to 21,000 additional troops.

A letter from 28 House Republicans urged Bush to divert some of the 21 Iraqi battalions operating in peaceful provinces to Baghdad and other dangerous areas, to spare U.S. troops.

White House press secretary Tony Snow said Bush's meetings with lawmakers were more than just window dressing.

He said, "The fact is, these meetings may not be happy-face, kumbaya, but they have been very constructive."