Much of the regular violence is attributed to Al Qaeda in Iraq, and in recent weeks the country has faced an increase in violence that has been clearly linked to the elections. Candidates have been assassinated, political gatherings have been targeted and, during Monday’s violence, two schools in Hilla that were to serve as polling sites were blown up by homemade bombs, although no one was killed because the schools were empty.

Later in the day, in Babel Province, whose capital is Hilla, security officials declared a state of emergency after revealing that they had received intelligence that armed groups were planning to carry out attacks at polling stations across the area.

On Saturday, nearly 700,000 members of Iraq’s security forces — the police and the army — cast ballots a week early, so they could be on hand to provide security next Saturday, when the rest of the country is scheduled to vote. The early vote was carried out free of violence. Martin Kobler, the United Nations representative to Iraq, released a statement praising the “smooth conduct” of the early vote. “It is of the utmost importance that voters turn out in an orderly and safe environment free of violence, threats and intimidation,” Mr. Kobler added in his statement.

The cabinet of Prime Minister Nuri Kamal al-Maliki had already postponed elections in two Sunni-dominated provinces, Anbar and Nineveh, where protests against Mr. Maliki’s government are continuing. The reason given for the delay was security, but nearly everyone involved in Iraqi politics — American diplomats, opposition politicians, United Nations officials, even Iraq’s own election officials — believe the decision was a politically motivated one by Mr. Maliki to forestall the election of Sunni candidates hostile to the Shiite-dominated central government.

Aside from the election-related violence, Iraq’s main Sunni insurgent group, Al Qaeda in Iraq, has strengthened itself in the period since American troops left at the end of 2011 and has spread its deadly operations beyond Iraq’s borders by fostering Al Nusra Front, the jihadist group that has become one of the most successful fighting units in Syria battling to topple the regime of Bashar al-Assad.