Updated

Iraq's parliament agreed to postpone a vote for a new president by a day on Wednesday as the extremist Islamic State group claimed responsibility for a suicide bombing in Baghdad the night before that killed 31 people, mainly civilians.

The delay is in response to a request from the Kurdish political bloc, Parliament Speaker Salim al-Jabouri said Wednesday addressing lawmakers.

With President Jalal Talabani's term set to expire, the vote for his successor is part of broader negotiations over forming a new government. At least 95 candidates are running, Shiite lawmaker Adel Shershab told state television.

The Sunni militants' capture of large areas of Iraq last month, including the second-largest city Mosul, plunged the country into its worst crisis since the withdrawal of U.S. troops in 2011. Calls are intensifying for Prime Minister Nouri al-Maliki to step down, with many accusing him of trying to monopolize power and alienating the Sunni minority. But the prime minister, who has held office since 2006, has vowed to remain in his post.

Despite the crisis, lawmakers have struggled to agree on a new government following April elections -- in which al-Maliki's bloc secured the most seats. After several delays, lawmakers elected a moderate Sunni as parliament speaker on July 15, the first step in the process.

"The parliament is meeting again in order to select the president of the republic in accordance with the constitutional and legal procedures that allow any citizen to run," al-Maliki said in his weekly address to parliament. "We hope that the parliament will succeed in choosing the president."

Talabani, who suffered a stroke in late 2012, returned to the country on Saturday after more than 18 months abroad for medical treatment.

Two names have emerged as front-runners to succeed Talabani -- former Deputy Prime Minister Barham Saleh and the Kirkuk provincial Gov. Najimaldin Karim.

Since 2003, Iraq's political parties have agreed to assign the position of president to a Kurd, prime minister to a Shiite and speaker of parliament to a Sunni.

The next president will task someone with forming a new government, and whoever can assemble a majority coalition will become the next prime minister.

Meanwhile, the Islamic State group claimed responsibility for a deadly attack on a checkpoint near a revered Shiite shrine in the heart of the capital late Tuesday, as worshippers awaited security checks before visiting the site during the Islamic holy month of Ramadan. Another 58 people were wounded in the attack, which took place in the central Kazimiyah district.

Police officials confirmed the toll, speaking on condition of anonymity because they were not authorized to talk to reporters.

In a statement posted online, the Islamic State group claimed the attack and said it was "in response to the hostility of the (Shiite-led) government" of al-Maliki and his "criminal militias, who spare no effort in fighting Islam and Muslims."

The authenticity of the statement could not be independently verified, but it was posted on a militant website frequently used by the group.

In the western province of Anbar, deadly clashes erupted Wednesday between government security forces and militants outside the city of Ramadi, killing eight militants, said Abdul-Karim al-Ani, a doctor at city's main hospital.

A report released Wednesday by New York-based Human Rights Watch also accused the Iraqi military of indiscriminately attacking alleged militant targets in airstrikes in several cities, killing at least 75 civilians and wounding hundreds. Military officials could not be immediately reached for comment.