BAGHDAD — Car bombs ripped through Shiite and Kurdish targets in Baghdad and other cities Wednesday, killing at least 66 people, wounding more than 200 and feeding growing doubts that Iraq will emerge as a stable democracy after decades of war and dictatorship.

The latest bloodshed came against a backdrop of sharpening political divisions that show Iraq has made little progress in healing the breach among its religious and ethnic communities that once pushed the country to the brink of civil war. The coordination, sophistication and targets of the attacks bore the hallmarks of al-Qaida and its Sunni militant allies seeking to exploit these tensions.

Iraqi authorities played down any suggestion that the devastating attacks that have taken place every few weeks or so since the U.S. military withdrew in mid-December portend a return to the all- out, tit-for-tat violence that tore the nation apart in 2006-07.

“Iraqis are fully aware of the terrorism agenda and will not slip into a sectarian conflict,” said Baghdad military command spokesman Col. Dhia al-Wakeel.

But Iraqi authorities have been unable to prevent such wide-scale attacks, even though they were on high alert during a major Shiite pilgrimage.

Altogether, 17 explosions struck Baghdad and six other cities and towns some 300 miles apart, from Mosul in the vast deserts of the north to Hillah in the fertile plains of the south.

The New York Times, citing unnamed officials, said more than 90 people were killed in the attacks.

Most targeted Shiite pilgrims between 5 a.m. and 8 a.m. as hundreds of thousands were making their way on foot to the capital.

The only large cities spared were the southern port city of Basra and the holy city of Najaf.

“I fell on the ground. Then so many people fell on me,” said Falah Hassan, who was being treated at Sheikh Zayid Hospital in Baghdad

Hours after the bombing in Hillah, puddles of blood and shards of metal still clogged a drainage ditch. Soldiers and dazed onlookers wandered near the charred remains of the car that exploded, gazing at the gaping holes in nearby shops.

Wednesday’s blasts were the third this week targeting the annual pilgrimage to observe the eighth-century death of Imam Moussa al-Kadhim, a revered saint who was the Prophet Muhammad’s great-grandson. The processions of the faithful, many waving green banners, will converge on a golden-domed shrine in Baghdad’s northern neighborhood of Kazimiya. The commemoration culminates Saturday.

Bombs also hit pilgrims in the cities of Taji near the capital and Karbala and Balad in southern Iraq. The Kurdish ethnic minority group also was targeted: Bombs struck the offices of two political parties in the northern city of Kirkuk.

Helicopters buzzed over Baghdad, and in hospitals, familiar and bloody scenes of grief unfolded.

Among the victims were those who had set up tents, including some Sunnis, to serve water and food to the pilgrims.

“The explosion was large enough to tell us that the target is all Iraqis, not just Shiites, because I had two Sunni friends helping me serve the pilgrims,” said Ali al-Baydhani, 39, who was operating a food stand.

One senior Iraqi intelligence officer acknowledged that the attacks — despite heightened security measures — showed the weakness of the military and police.

Another officer, the chief of military intelligence, said the carnage could have been even worse if security forces had not seized two explosivesladen vehicles in Baghdad and Taji early in the morning, including a truck full of watermelons hiding nearly a ton of explosives. Both officials spoke on condition of anonymity to protect their families.

In the afternoon, the government declared that today would be a day off so that the army and police can secure the capital.

The overall toll made Wednesday the deadliest day in Iraq since Jan. 5, when a wave of bombings targeting Shiites killed 78 people in Baghdad and outside the southern city of Nasiriyah.

The level of violence has dropped dramatically in Iraq since the height of the war, though Shiite religious events are often targeted. One front-page article in a local newspaper Wednesday heralded the return of women to local cinemas. Lately, new red double-decker buses have begun operating in Baghdad, and checkpoints and blast walls have been dismantled, providing some relief to the city’s notorious traffic delays. The recent opening of a department store has given some hope to residents of the formerly terrifying Baghdad neighborhood of Adhamiyah.

But the weakness of Iraq’s security apparatus, the government’s inability to provide even basic services such as electricity and the dysfunctional political scene foster pessimism.

Six months after the departure of the last U.S. forces, Iraq’s prospects of quickly transforming into a functioning democracy are further dimming.

Prime Minister Nouri al-Maliki, a Shiite, is under fire for breaking promises to share power with his partners in a unity government and focusing on settling old scores. Tensions spiked after Vice President Tariq al-Hashemi, the highest-ranking Sunni in Iraq’s leadership, was charged with running death squads. The government began his trial in absentia with al-Hashemi out of the country.

“The al-Qaida elements in Iraq are feeling like they are in a position to try to start something bigger in Iraq and they are trying to do so. They are increasingly going after Shiite targets to try to reignite the civil war,” said Kenneth Pollack, a senior researcher at the Brookings Institution’s Saban Center for Middle East Policy.

Meanwhile, a lethargic parliament has failed to take up important bills such as regulating the sharing of oil revenue with the northern Kurdish region. Red tape stifles economic growth. Sunnis complain of discrimination and disenfranchisement.

Iraq’s oil riches — an income of tens of billions of dollars a year — are effectively cushioning the lack of effective government and preventing the country from becoming a failed state like Somalia.

On Wednesday, al-Maliki led a meeting of his top commanders and warned in a statement that the political crisis engulfing his government might be encouraging insurgents to unleash attacks.

Still, despite the political crisis, there are some signs of progress that attacks like Wednesday’s have not managed to erase, said Joost Hiltermann, deputy Middle East program director for the International Crisis Group.

He noted that al-Maliki, for all his missteps, is still in control of the government and that the tensions, while escalating, have not yet shown signs of a return to the sectarian battles of the past, when bombings and attacks happened several times a day and people were afraid to leave their homes.

“The political parties are still agreeing to work out their problems through a democratic process,” he said. “That’s why there’s talk of a no-confidence vote in parliament and not about shooting people.”

In Washington, meanwhile, a battle is brewing over President Barack Obama’s pick to be the next U.S. ambassador to Iraq, with Senate Republicans calling for the nomination to be withdrawn and the White House and former envoys to Iraq defending it.

Six Republican members of the Senate Foreign Relations Committee sent a letter Wednesday to Obama calling on him to withdraw Brett McGurk’s nomination.

They cited concerns about McGurk’s abilities and judgment over allegations that he acted inappropriately while working at the U.S. Embassy in Baghdad during President George W. Bush’s second term.

In the letter, they said Mc-Gurk “lacks the leadership and management experience” needed for the job.

The White House said it was standing by McGurk’s nomination, which also was supported by the current ambassador to Iraq and his two predecessors.

In a letter to the Democratic chairman and the top Republican on the foreign relations panel, the current U.S. ambassador to Iraq, James Jeffrey, and former envoys Christopher Hill and Ryan Crocker defended McGurk and expressed their “enthusiastic support” for his nomination.

Earlier, Sen. John Kerry, D-Mass., the chairman of the committee, hinted that the nomination could be reconsidered. He said he had spoken with Vice President Joe Biden about McGurk. “I think there are some very fair questions being asked and they need to be answered,” Kerry said.

The six Republican senators said their “strong concerns” about McGurk’s qualifications were amplified by e-mails detailing what they called his “unprofessional conduct.”

The e-mails in question indicate that McGurk had an intimate relationship with a Baghdad-based American journalist while he was married to another woman and working at the embassy there in 2008. McGurk has since married the reporter, Gina Chon, who resigned Tuesday from The Wall Street Journal after acknowledging that she violated in-house rules by showing McGurk unpublished stories. McGurk has not responded to requests for comment.

The senators’ letter was signed by Jim DeMint of South Carolina, James Risch of Idaho, John Barrasso of Wyoming, Mike Lee of Utah, Marco Rubio of Florida and James Inhofe of Oklahoma.

The Senate Foreign Relations Committee is scheduled to vote on McGurk’s nomination Tuesday. From there it would be sent to the full Senate for a vote.

Information for this article was contributed by Kay Johnson, Sinan Salaheddin, Matthew Lee, Donna Cassata and Julie Pace of The Associated Press and by Tim Arango, Zaid Thaker, Duraid Adnan, Yasir Ghazi and employees from Baghdad, Hillah, Mosul, Kirkuk, Samarra, Fallujah and Ramadi for The New York Times.

Front Section, Pages 1 on 06/14/2012