Nabil al-Jurani, Associated Press
A police officer searches a Shiite pilgrim on his way to visit the Imam Ali shrine, cousin of Prophet Muhammad, to mark the anniversary of the Prophet Muhammad's death in Basra, Iraq's second-largest city, 550 kilometers (340 miles) southeast of Baghdad, Iraq, Sunday, Jan. 22, 2012.

BAGHDAD — Two separate car bombs exploded in a Shiite district in eastern Baghdad on Tuesday, police officials said, killing eight people as violence surges in Iraq amid an escalating political crisis a month after the U.S. military withdrawal.

A wave of bombing attacks has killed at least 170 people since the beginning of the year, many of whom were Shiite pilgrims attending religious commemorations. The last American soldiers left the country Dec. 18.

Suspected Sunni insurgents have frequently targeted Shiite communities and Iraqi security forces to undermine public confidence in the Shiite-dominated government and its efforts to protect people.

Tuesday's first attack targeted an early morning gathering of day laborers in Baghdad's Sadr City. Police said seven were killed and another 21 wounded. Minutes later, an explosives-packed car blew up near a pastry shop in the same district, killing one civilian and wounding 11 others, police said.

Hospital officials Baghdad confirmed the death toll. All officials spoke on condition of anonymity because they were not authorized to brief the media.

While insurgents have carried out a number of deadly attacks in recent years, there is little indication yet that the country is slipping back towards the widespread sectarian bloodshed of 2006 and 2007.

Nonetheless, these attacks are seen as particularly dangerous because they coincide with both the departure of U.S. troops, as well as a political crisis pitting Shiite officials against the largest Sunni-backed bloc.

The political battle erupted last month after the Shiite-led government issued an arrest warrant against the Sunni vice president, Tareq al-Hashemi, on terrorism charges, sending him into virtual exile in the Kurdish autonomous region in northern Iraq. In protest, al-Hashemi's Sunni-backed Iraqiya bloc has been boycotting parliament and Cabinet sessions, bringing government work to a standstill.

Sunnis fear that without the American presence as a last-resort guarantor of a sectarian balance, the Shiite government will try to pick off their leaders one by one, as Prime Minister Nouri al-Maliki tries to cement his own grip on power.

Last week, the leader of the Sunni-backed Iraqiya bloc, Ayad Allawi, accused al-Maliki of unfairly targeting Sunni officials and deliberately triggering a political crisis that is tearing Iraq apart. Allawi, who is a Shiite, said Iraq needs a new prime minister or new elections to prevent the country from disintegrating along sectarian lines.