Two powerful suicide car bombs blew up outside the Justice Ministry and city government offices in downtown Baghdad Sunday, killing at least 147 people in the deadliest attack in more than two years. Iraqi leaders said the attacks aimed to disrupt political progress in the months leading up to January's crucial elections.

While violence has dropped dramatically in the country since the height of the sectarian tensions, the latest bombings underscored the precarious nature of the security gains and the insurgency's abilities to still pull off devastating attacks in the center of what is supposed to be one of Baghdad's most secure areas.

The street where the blasts occurred had just been reopened to vehicle traffic six months ago. Shortly after, blast walls were repositioned to allow traffic closer to the government buildings.

Such changes were touted by Iraq's prime minister as a sign that safety was returning to the city.

"The perpetrators of these treacherous and despicable acts are no longer hiding their objective but to the contrary, they publicly declare that they are targeting the state ... and aiming at blocking the political process, halting it and destroying what we have achieved in the last six years," President Jalal Talabani said.

President Barack Obama condemned the "outrageous attacks," saying they "reveal the hateful and destructive agenda of those who would deny the Iraqi people the future that they deserve."

Secretary of State Hillary Rodham Clinton said the "savage" suicide bombings attacks will not succeed in undermining Iraq's progress toward stability, self-reliance and justice based on the rule of law.

There have been no claims of responsibility so far, but massive car bombs have been the hallmark of the Sunni insurgents seeking to overthrow the country's Shiite-dominated government.

Iraqi Prime Minister Nouri al-Maliki blamed al-Qaida and members of deposed regime of Saddam Hussein for the blasts aiming to "block the political process and the elections."

"The cowardly terrorist acts will not break the will of the Iraqi people to continue the political process," al-Maliki said in a statement.

Black smoke billowed from the frantic scene, as emergency service vehicles sped to the area to treat the nearly 600 wounded.

Even civilian cars were being commandeered to transport the wounded to hospitals.

"The walls collapsed and we had to run out," said Yasmeen Afdhal, 24, an employee of the Baghdad provincial administration, which was targeted by one of the car bombs. "There are many wounded, and I saw them being taken away. They were pulling victims out of the rubble, and rushing them to ambulances."

At least 25 staff members of the Baghdad Provincial Council, which runs the city, were killed in the bombing, said council member Mohammed al-Rubaiey. Three American contractors were among the wounded.

The provincial council is the city government, which oversees a broad range of city services including distribution of food ration cards, a holdover from Saddam-era sanctions against Iraq. The council also administers garbage collection, electricity and the distribution of fuel for generators and is responsible for the maintenance of the cities schools. It is composed of 57 directly elected representatives.

The blasts are a blow to Prime Minister Nouri al-Maliki, who has staked his reputation and re-election hopes on returning security to the country.

The attacks came as Iraq was preparing for elections scheduled for January. Officials have warned that violence by insurgents intent destabilizing the country could rise.

UN Secretary-General Ban Ki-moon urged "all Iraqis to unite in the face of these deplorable acts and to work with heightened urgency to protect Iraq's political progress."

The area where the blasts occurred is just a few hundred yards from the Green Zone that houses the U.S. Embassy as well as the prime minister's offices.