BAGHDAD, Iraq — A leading Sunni politician said Friday his party would be open to an alliance with secular Shiites and Kurds to form a coalition government to run the country once the results are in from this week's parliamentary elections.

"We will not accept the exclusion of any segment of the Iraqi people unless they themselves don't want to participate," said Adan al-Dulaimi, a former Islamic studies professor who heads a Sunni Arab bloc that is now expected to have power in parliament.

In a joint statement, the two senior U.S. officials in Iraq offered congratulations on the successful election and called for unity as the country approaches formation of a new government.

The statement by U.S. Ambassador Zalmay Khalilzad and top U.S. commander Gen. George Casey Jr., said "more needs to be done" to overcome differences to "build bridges for national unity and establish an effective, broad-based government."

"We urge all Iraqis to pursue their objectives peacefully through the political process," the statement said.

U.S. officials view al-Dulaimi, who heads an alliance called the Iraqi Accordance Front, as a possible intermediary who could persuade some Sunni-led insurgent groups in restive Anbar province to join the political process after boycotting previous votes.

In an interview with The Associated Press, Al-Dulaimi predicted that Shiite religious parties would be unable to form a government — even though they are widely expected to take the largest number of seats.

That would open the door to a coalition of Sunnis, secular Shiites and Kurds, al-Dulaimi said.

However, al-Dulaimi's prediction that the Shiites would be unable to form a government is by no means a certainty. Shiites account for about 60 percent of the country's 27 million people, and turnout in the Shiite heartland of southern and central Iraq was reported high.

Under the newly ratified constitution, the party with the biggest number of seats gets first crack at trying to form a government than can win parliament's endorsement. That is likely to be the coalition of Shiite religious parties that dominate the outgoing government.

Still, a government with strong Sunni Arab representation could help defuse the Sunni-dominated insurgency and allow the United States and its coalition partners to begin removing troops next year.

In an Internet statement Friday, the Islamic Army in Iraq, a major insurgent group, said it was responsible for the absence of widespread election violence because it wanted to avoid harming Sunni Arab voters.

"We knew Sunnis would participate in this game (because) most were forced to through the oppression, torture and destruction and suffering they receive from the slaves of the Cross (the Americans) and the Shiites," said the statement, which could not be immediately verified.

The statement added that the jihadist group did not believe in democracy, only God.

Also Friday, the U.S. military said Iraqi authorities have issued an arrest warrant for Mullah Halgurd Al-Khabir, the "prime suspect" in the August 2003 bombing of the U.N. headquarters in Baghdad that killed 22 people. The statement identified al-Khabir as the Baghdad area commander for the Islamic militant Ansar al-Sunnah Army, which has ties to al-Qaida in Iraq.

Before Thursday's election, Shiite religious politicians said they expected to win up to 120 seats — down 26 from their current level. The Shiites and Kurds won a disproportionate number of seats in the January ballot because so many Sunnis boycotted the election. This time, Sunnis turned out in large numbers.