Rival Shi'ite and Sunni groups are massing their militias in expectation of major confrontations, Iraqis say, even as President Bush prepares to meet today with the nation's embattled prime minister, Nouri al-Maliki.
Mr. Bush's meeting in Jordan is part of a wider attempt to involve Iraq's neighbors in efforts to end Iraq's vicious sectarian violence before it spills over into a larger regional conflict.
But Iraqis on both sides of their nation's sectarian divide report worrisome signs that the conflict will soon evolve into pitched battles between large armed groups.
One secular Shi'ite speaking on the telephone from Baghdad said Shi'ite militias were massing in preparation for a large offensive against Sunnis in the capital.
"They had a big militarylike ceremony today for the Mahdi militia, to show their force. They are making themselves ready for something big -- protests, fighting, killing," said the Shi'ite.
A secular Sunni in close contact with one insurgent faction, said rebel Sunnis were also trying to form alliances among militias for a big push in the city against the Shi'ites, including more raids on government buildings.
"I am waiting for the Sunnis to launch a 'Tet Offensive.' That is the one plug they have not pulled yet, and I could see that happening," said senior Rand defense analyst Ed O'Connell.
The Tet Offensive was a series of attacks by the North Vietnamese and their Viet Cong allies that many consider a turning point in the war, leading eventually to the U.S. withdrawal.
Any emergence of pitched battles between massed groups of Sunnis and Shi'ites would largely settle a long-running argument in Washington over whether the conflict in Iraq should be described as a civil war -- a description the Bush administration has so far rejected.
However the depth of concern over the rising levels of violence is evident in the flurry of diplomacy leading to Mr. Bush's meeting with Mr. al-Maliki in Amman today.
Vice President Dick Cheney met with King Abdullah in Saudi Arabia on Saturday, and Iraqi President Jalal Talabani held talks Monday and yesterday with Iranian President Mahmoud Ahmadinejad and religious leader Ayatollah Ali Khamenei.
Both Iranian leaders pledged to help Iraq, but sharpened the political divisions with the United States by accusing Washington of destabilizing the region by supporting Sunni "outlaws."
King Abdullah II of Jordan, meanwhile, has said that "something dramatic" must come out of the meeting because Iraq is "beginning to spiral out of control."
While the Bush administration has been reluctant to recruit clearly hostile regimes in Tehran and Damascus into the Iraq effort, many analysts have concluded that there is no other choice.
"The only people who are going to be able to put this back into the box are not the American politicians or American military -- it is the Iranians, the Syrians, the Jordanians and the Saudis," said Mr. O'Connell.
An adviser to the Iraq Study Group, headed by former Secretary of State James A. Baker III, said any talks with Iran must deal more with the violence in Iraq than with Tehran's nuclear program.
If Mr. Cheney's meeting with the Saudis "was more about Iraq -- rather than Iran and the nuclear issue -- that would be a more hopeful sign," said the former U.S. military officer who would only speak on the condition of anonymity because of his involvement with the Iraq Study Group.
"There might be some indication that the administration is having dialogue with Iran about Iraq," he said.
Mr. al-Maliki is expected to ask Mr. Bush to set a timetable for removing U.S. troops from Iraq, although there are deep disagreements in Washington whether that would make matters better or worse.
There are also serious questions as to how much control Mr. al-Maliki has over his own government and country.
"Al-Maliki is heavily under the sway of [radical Shi'ite cleric Muqtada] al-Sadr. He is afraid of al-Sadr, is kowtowing to the Iranians, has no idea of how to deal with the United States, and is the worst possible candidate to lead the country out of this mess," said Mr. O'Connell.
Iraqis in Baghdad note that Mr. al-Maliki was pelted with rocks on Sunday when he went to visit grieving families in Sadr City -- once the base of his support.
Mr. Bush is expected to publicly reiterate his support for Mr. al-Maliki, but privately push the Iraqi leader to take effective action against the Shi'ite militias, particularly the Mahdi Army of Sheik al-Sadr.
"You are faced with the fact that Sadr has to be stopped, or you have to concede the battle of Baghdad to him," said security analyst Robert Killebrew.
"In the past 30 days, what we've got is the Sadr militia openly trying to take over Baghdad and run the Sunnis out, and we simply can't tolerate Sadr any longer," Mr. Killebrew said. "He has emerged as our number one problem in Iraq."