Just ahead of President Bush's meeting with Iraqi Prime Minister Nouri al-Maliki, senior U.S. commanders are revising their strategy for securing Baghdad.

Maliki is in Washington, D.C., on Tuesday for his first visit to the United States since taking office two months ago. He will meet with Bush, Defense Secretary Donald Rumsfeld and other top U.S. officials. His visit comes after one of the bloodiest weekends in Iraq in months, with more than 150 Iraqis killed in a series of car bombings.

In a prelude to his discussions with Bush, the prime minister penned an editorial in The Wall Street Journal praising al-Muthanna in southern Iraq, the first province to assume complete responsibility for its security independent of coalition troops. But, Maliki noted troubles in Baghdad.

"Security plans to quell the violence in Baghdad, our capital and most populous city, face serious challenges that must be overcome," he wrote.

In a meeting with British Prime Minister Tony Blair in London on Monday, Maliki confirmed United Nations statistics showing that an average of 100 Iraqi civilians per day were killed in May and June this year. Most of them were victims of sectarian militias.

"They kill according to this sectarian scenario. There is an overwhelming feeling amongst political leaders in Iraqi society that those people must be stopped, we must strike at them, because we will never allow the country to slide into a civil or sectarian war," Maliki said.

To that end, senior Bush administration officials confirmed Monday that as many as 5,000 more U.S. troops will be heading to Baghdad from other parts of the country, and more U.S. troops will soon be deployed there to help deal with what is viewed as a failed six-week-old Baghdad security plan by Iraq's new government.

"It's pretty clear that there's an attempt in Baghdad to create as much chaos and havoc as possible. And it's important to make sure that we address this," White House press secretary Tony Snow said.

Snow added that it is clear that the previous plan to bolster security, praised by Bush during a surprise visit to Baghdad on June 13, "has not achieved its objectives."

"As often happens, conditions on the ground force one to adjust strategies and adapt to changing realities, and that's what we're trying to do," Snow said.

About 55,000 U.S. troops are already in Iraq's capital city. One brigade — made up of about 3,500 active duty soldiers now based in Germany but put on hold in May — has now been ordered to deploy to Iraq.

A senior Defense Department official said the remainder of a backup force that had been stationed in Kuwait was also heading into Iraq. Some U.S. military police companies are being shifted to Baghdad, involving between 500-1,000 troops, as well as a cavalry squadron and a battalion of field artillery troops, said the official, who requested anonymity because the plans yet to be made public.

An Army spokesman added that no decisions have been made to cancel the scheduled deployments of any of the units announced for the next rotation, which will get underway in the coming weeks and will involve up to 21,000 troops.

A Pentagon official acknowledged a stepped-up push by U.S. and Iraqi forces across Baghdad that began last month failed to produce intended results. The death of Iraq's most wanted terrorist, Abu Musab al-Zarqawi, has also not helped to mitigate deadly attacks in ways U-S officials had hoped.

In June, several military officials said they believed Gen. George Casey, the leader of the Multinational Force in Iraq, was considering a slight reduction in U.S. troop levels this year, perhaps by withholding the deployment of two brigades this fall.

At the time Casey told reporters he was confident "that we'll be able to continue to take reductions over the course of this year." But since that time, the security situation has deteriorated in Baghdad.

"We have articulated the Baghdad strategy of terrorists and insurgents. We will do whatever it takes to bring security to Baghdad," said Maj. Gen. William Caldwell, the coalition spokesman.

But even with the military support, Bush and Maliki are not eye-to-eye on every issue. Maliki, a former Shiite activist who spent years in exile in Syria, has been critical of Bush for siding with Israel and not supporting an immediate cease-fire to the fierce Israeli-Hezbollah fighting. Maliki told reporters he would convey that message personally to Bush.

On the flip side, Senate Democrats are complaining that Bush and the United States have been so preoccupied by the conflict between Hezbollah terrorists and Israeli Defense Forces, that not enough attention is being paid to events on the ground in Iraq. They add that 2006 was supposed to be a "year of significant change," but no efforts seem to be aimed toward that end.

"It is time for the Iraqi prime minister to move beyond vagaries and develop a viable strategy to deal with the militias and prevent Iraq from descending into full-scale civil war," said Sen. Ted Kennedy, D-Mass.

"When President Bush meets with Prime Minister Maliki tomorrow, the president should ask him two critical questions: does the Iraqi government have a credible plan to disarm and demobilize the militias and reintegrate as many of their members as possible into government security forces? Can the Iraqi government obtain a real commitment from the political parties to disarm and disband the militias?"

"This is a civil war," said Senate Majority Leader Harry Reid of Nevada. He renewed his call for U.S. troops to be re-deployed from Iraq by the end of this year, saying that message has to be given to Maliki.

"When he's here, we need President Bush to communicate that our commitment in Iraq is not unlimited. He needs to announce a change of course in his failing policy," Reid said.

Followers of radical Shiite cleric Muqtada al-Sadr also denounced the Iraqi prime minister's trip, coincidentally and unintentionally lining up with Senate Democrats.

"We want him to cut his visit and not to sign any paper leading to occupation forces remaining in Iraq," said the statement by the al-Sadr movement. Al-Sadr's followers hold 30 of the 275 seats in Iraq's parliament and control five Cabinet ministries including health.

Snow refused to be drawn into the debate over whether the rising sectarian violence in Iraq constitutes civil war.

"The focal point right now for terror in Iraq is the area in and around Baghdad, and that obviously is going to be a high priority for the president and the prime minister," Snow said. "I'm not going to get into back-and-forthing with members of Congress. It's an election year."

Bush did not publicly discuss the situation in Iraq on Monday. Instead, the president talked immigration policy on Monday, presiding over a citizenship ceremony at Walter Reed Army Medical Center for three soldiers wounded in Iraq.

"We gain three new citizens today, men who knew the cost of freedom and are willing to pay that cost so others can live free," he said. Currently, 33,000 non-U.S. citizens serve in the military. After the Sept. 11, 2001, terror attack, Bush signed an executive order making foreign-born members of the U.S. military immediately eligible for U.S. citizenship when they serve on active duty.

Meanwhile, House Democrats launched their own offensive on Monday, crafting a letter to House Speaker Dennis Hastert urging him to cancel a planned speech by Maliki to the chamber. The letter reads that Maliki and other members of the Iraqi leadership have denounced Israel, and are at odds with U.S. foreign policy goals. Maliki, therefore, should not be given the honor of giving an address from the speaker's podium.

"In recent months there have been extensive reports indicating that Maliki and many in the Iraqi leadership are increasingly influenced by the government in Iran. Further, they have expressed support of terrorist organizations such as Hamas and Hezbollah, the latter of which was responsible for the death of 241 United States Marines in Beirut. The House should not allow an address from any world leader who has taken such action," the letter reads.

"We are unaware of any prior instance where a world leader who actively worked against the interests of the United States was afforded such an honor. We urge you to cancel the address," the letter concludes.

FOX News' Bret Baier, Nick Simeone, Jim Mills and The Associated Press contributed to this report.