A suicide car bomb hit a bus packed with Iraqi National Guards on Sunday, killing 26 people in the deadliest attack of its kind in four months on Iraqis cooperating with U.S. forces to secure a Jan. 30 election. Two bombers in an explosives-laden vehicle veered into the path of the bus and blew it up outside a U.S. military base near the town of Balad, north of Baghdad. Hours later, insurgents killed three policemen on patrol close to neighbouring Samarra, and shot dead a member of the city's governing council as well as his driver and bodyguard. A National Guard officer said the car bomb killed 25 soldiers on the way to their posts. Relatives wept over the men's bodies at a local mosque. A civilian bystander also died in the blast. U.S. and Iraqi officials ushered in the New Year with warnings of an expected spike in pre-election assaults by insurgents trying to drive out U.S.-led forces and topple Iraq's American-backed government. "Those responsible for this attack ... are trying to prevent democracy in Iraq," said Major Neal O'Brien, a military spokesman in Tikrit. "They will not be successful." Sunday's bombing was the deadliest suicide attack against Iraqi security services since mid-September, when at least 47 people were killed outside a Baghdad police station. Guerrillas have killed hundreds of security force members since the U.S.-led invasion in 2003. Many Iraqis wonder how police and National Guards will be able to protect voters when they can barely protect themselves.