BAGHDAD, Iraq (AP) – A car bomb exploded Wednesday evening as worshippers left a Shiite Muslim mosque northeast of Baghdad, killing 22 people and wounding about 60, police said. The U.S. military reported the combat deaths of four more American soldiers.

The blast occurred near a mosque in the village of Huweder, located in a mixed area of Sunni and Shiite Muslims about 45 miles northeast of Baghdad, police Lt. Col. Falah al-Mohammedawi said.

No group claimed responsibility for the blast, which was the second major attack in the village in six months. A bomb hidden in a truck carrying dates exploded there Oct. 29, killing 30 people.

Rising sectarian tensions have led to a sharp rise in sectarian violence since the Feb. 22 bombing of a major Shiite shrine in Samarra that triggered reprisal attacks against Sunni mosques and clerics.

U.S. officials have been urging Iraqi politicians to speed formation of a new national unity government as a first step toward combating the violence. But talks among the major parties have deadlocked over demands by Sunni and Kurdish politicians that the Shiites withdraw their nomination of Prime Minister Ibrahim al-Jaafari to head the new government.

In a move to break the deadlock, acting parliament speaker Adnan Pachachi, a Sunni Arab, told a nationally televised press conference Wednesday that he would convene parliament Monday in an effort to pressure movement in the stalled talks.

“It is my duty to the Iraqi people in order to preserve the credibility of the democratic process,” Pachachi said.

Pachachi said Shiite politicians told him they hoped to have the break the deadlock in time for Monday’s session.

“There are indications that cause us to be optimistic that an agreement will be reached on all the sticking points regarding forming a national unity government,” the former foreign minister said.

Casualties among U.S. forces have risen in recent weeks. In March, 31 U.S. service members died in Iraq, the lowest monthly figure since February 2005, according to an Associated Press count. So far this month, the U.S. death toll stands at 35.

Three U.S. soldiers were killed Wednesday in roadside bombings – two south of Baghdad and a third on patrol east of the capital, the U.S. military said.

The military also reported that an American soldier from the 101st Airborne Division died Monday from a “non-battle injury” near Tal Afar in northern Iraq.

At least 2,362 U.S. personnel, including seven civilians working for the military, have died since the beginning of the war in 2003, according to AP’s count.

Key Shiite leaders said a parliamentary session was unlikely until they had decided who gets top posts, including prime minister.

“Things don’t look good right now,” said Ridha Jawad Taqi, a leading figure in the biggest Shiite party. “We cannot go to parliament if there’s no agreement” on key posts, including the presidency.

Shiites get to nominate the prime minister because they are the largest bloc, but the presidency, parliament speaket and some Cabinet posts are to go to different religious and ethnic groups.

“If we haven’t reached an agreement, what will we do in this session?” asked Haidar al-Obaidi, a senior official in al-Jaafari’s Dawa party.

Another Shiite lawmaker, Khaled al-Attiyah, said that Pachachi was simply trying to pressure the Shiites to resolve the al-Jaafari issue.

Iraqis are growing frustrated over the lack of progress on a government. An editorial cartoon Wednesday in the newspaper Al-Sabah al-Jedid depicted an enormous turtle struggling to move with a group of politicians on its shell. “Expediting the political process,” the caption read.

Associated Press writers Qassam Abdul-Zahra and Mariam Fam contributed to this report.