BAGHDAD -- Insurgents deployed a series of car bombs in highly coordinated attacks that cut across a wide swath of Iraq Monday, killing at least 55 on the deadliest day in nearly a month.

The assault bore the hallmarks of a resurgent al-Qaida in Iraq and appeared aimed at sowing fear, days before the first elections since U.S. troops withdrew. There was no immediate claim of responsibility, but coordinated attacks are a favorite tactic of al-Qaida's Iraq branch.

Iraqi officials believe the insurgent group is growing stronger and increasingly coordinating with allies fighting to topple Syrian President Bashar Assad. They say rising lawlessness on the Syria-Iraq frontier and cross-border cooperation with a Syrian group, the Nusra Front, has improved the militants' supply of weapons and foreign fighters.

The intensifying violence, some of it related to the provincial elections scheduled Saturday, is worrying for Iraqi officials and Baghdad-based diplomats alike.

At least 14 candidates have been killed in recent weeks, one slain in an apparent ambush Sunday.

Iraqi Army Maj. Gen. Hassan al-Baydhani, the No. 2 official at Baghdad's military command, said authorities managed to defuse three car bombs in Baghdad.

Monday's attacks, mostly car bombings, were unusually broad in scope. Among the places where attacks erupted were the Sunni-dominated western Anbar province and Saddam Hussein's hometown of Tikrit, the ethnically contested oil-rich city of Kirkuk and towns in the predominantly Shia south.

The deadliest attacks hit Baghdad, where multiple car bombs and other explosions killed 25 people.

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