Police in Baghdad have found some 50 bodies with gunshot wounds over the past 24 hours.
Sectarian death squads have made the Iraqi capital a killing field and many of the bodies had been bound and tortured.
UN Secretary General Kofi Annan has declared Iraq's plight as being worse than civil war.
In an interview yesterday, outgoing UN chief Mr Annan said: "When we had the strife in Lebanon and other places, we called that a civil war - this is much worse." He agreed with Iraqis who said life was worse now than it was under deposed president Saddam Hussein.
"If I were an average Iraqi obviously I would make the same comparison - that they had a dictator who was brutal, but they had their streets, they could go out, their kids could go to school and come back home without a mother or father worrying 'Am I going to see my child again?'" Mr Annan added.
President Bush will today host one of the most powerful leaders of the Muslim Shia majority, Abdul Aziz al-Hakim, who strongly denies charges that his supporters are among those who carry out assassinations.
Mr Hakim's SCIRI movement maintains close ties to US adversaries in Shia Iran where the party was founded. Mr Bush will also meet Iraq's Sunni vice president this month.
The White House meeting for Mr Hakim is seen by some analysts as a sign of Mr Bush delving more deeply into Iraqi politics in the quest for a new strategy that can stabilise Iraq and allow US troops go home.
In Washington yesterday, it was revealed that former defense secretary Donald Rumsfeld acknowledged in a memo just before he lost his job that the US strategy was not working and that it might be better to reduce troop numbers.
The Rumsfeld memo, written a day before Republicans lost control of Congress, read: "It is time for a major adjustment. Clearly, what US forces are currently doing in Iraq is not working well enough or fast enough."
Mr Rumsfeld, a leading planner of the Iraq war, outlined several options but endorsed none. Among them were reductions in US forces and bases and a revision of the US goals there. He suggested cutting US bases to just five from 55 by mid-2007.
Mr Bush met Shia Prime Minister Nuri al-Maliki last week and assured him of his backing. They agreed to speed up training for Iraqi forces, which Mr Maliki said could be in command of the country by June - despite qualms among US commanders about the effectiveness and sectarian loyalties of many Iraqi units.
Following a heavy defeat for his Republicans in last month's congressional elections, and two years before the party tries to retain the White House, Mr Bush is expected to consider proposals to be made on Wednesday by the bipartisan Iraq Study Group co- chaired by former secretary of state James Baker.