The No. 2 U.S. commander in Iraq said Tuesday that the next three to four months will be crucial in determining whether the United States can start to withdraw troops from Iraq without sacrificing security gains since the troop buildup began early this year.

Lt. Gen. Raymond Odierno said the number of attacks in August fell to their lowest level in more than a year, although he gave no figures. Odierno insisted that overall violence was declining — a sign that the buildup ordered by President Bush was working.

"I think the next three to four months are critical," Odierno told reporters. "I think that if we can continue to do what we are doing, we'll get to such a level where we think we can do it with less troops."

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Bush himself raised the possibility of a reduction in the 160,000-strong U.S. force during his surprise visit Monday to al-Asad Air Base in Anbar province, where Sunni Arab sheiks have been turning against Al Qaeda in Iraq.

Bush said U.S. Ambassador Ryan Crocker and the top commander Gen. David Petraeus "tell me if the kind of success we are now seeing continues, it will be possible to maintain the same level of security with fewer American forces."

Crocker and Petraeus will report to Congress next week on security and political progress since Bush dispatched 30,000 extra troops to Iraq to curb sectarian warfare. Petraeus is expected to point to a dramatic decline in violence in Anbar province thanks to a grass-roots revolt against Al Qaeda.

On Tuesday, an Al Qaeda front group announced on an Islamist Web site that it was forming new suicide battalions to strike at the Americans and their "renegade" allies — an apparent response to the burgeoning revolt against the terror movement.

"These battalions, with God's help, will perform their duties in an excellent manner during the month of Ramadan and the enemies of God will suffer a lot," the statement said, referring to the Islamic season of fasting that begins in about two weeks.

Odierno said U.S. forces were alert to the possibility of increased attacks during Ramadan but in the run-up to the holy month "violence has been going down."

The optimistic tone of recent U.S. statements appears aimed at persuading moderate Republicans in Congress to stand by the president and resist Democratic calls to begin bringing the troops home as soon as possible.

U.S. officials acknowledge privately they have not turned the corner in restoring security, even as they insist that trends are favorable. Last month, civilian deaths across Iraq rose to at least 1,809, the second highest monthly total this year, according to figures compiled by The Associated Press.

Early Wednesday in Baghdad, a roadside bomb exploded on the fringes of the Shiite slum of Sadr City, killing at least 11 and injuring 19, police and hospital workers said.

Blood stained the ground around a small crater caused by the bomb, which exploded shortly before 8 a.m. in an area where minibuses were stopped to pick up people heading to work in the eastern Baghdad neighborhood of Baladiyat, near Sadr City's al-Hamza square, a police officer said on condition of anonymity.

Video from Associated Press Television News showed the scene strewn with broken glass and littered with people's slippers and other items.

At least 42 people were killed or found dead across the country Tuesday, according to police reports.

The Electricity Ministry announced Tuesday that eight of its engineers and technicians were kidnapped and murdered the day before by unknown gunmen in east Baghdad.

The eight were traveling to a training session out of town when they were abducted. Relatives identified their bullet-riddled bodies in a hospital, ministry spokesman Aziz al-Shamari said.

In Mosul, 225 miles northwest of Baghdad, gunmen ambushed a car in the city center Tuesday, killing three men and a woman, police Brig. Gen. Abdul-Karim al-Jubouri said.

Despite some improvements in security, Iraqi politicians have made little progress in reaching power-sharing agreements among Shiites, Sunnis and Kurds — considered essential to lasting peace.

Iraq's parliament reconvened Tuesday after a much-criticized monthlong summer break. Lawmakers refused to give up their holiday despite outrage in the United States, where American officials and commentators complained that Iraqis were vacationing while American troops were dying.

Parliament in July shrugged off calls from Prime Minister Nouri al-Maliki to cancel the summer break, saying there was no point waiting any longer for the Cabinet to deliver draft legislation.

Deputy speaker Khaled al-Attiyah told the AP that the assembly had not yet received promised draft legislation to ease the ban on former Saddam Hussein supporters holding government jobs — a key demand of Sunni Arabs.

He also said he did not expect parliament to begin debating a draft bill on sharing the nation's oil revenue before mid-September.

Both bills are among the 18 benchmarks which the United States set down to measure political progress.

Also Tuesday, an appeals court upheld death sentences imposed against "Chemical Ali" al-Majid and two other Saddam lieutenants convicted of crimes against humanity for their roles a massacre of Kurds in the late 1980s.

Under Iraqi law they must now be hanged within the next 30 days.

In addition to al-Majid, the Iraqi High Tribunal upheld death sentences of former defense minister Sultan Hashim Ahmad al-Tai and Hussein Rashid Mohammed, a former deputy director of operations for the Iraqi armed forces.

Al-Tai negotiated the cease-fire than ended the 1991 Gulf War, when a U.S.-led coalition drove Iraqi forces from Kuwait.

Complete coverage is available in FOXNews.com's Iraq Center.