The glitch-plagued rollout of President Barack Obama's health care overhaul was the top news story of 2013, followed by the Boston Marathon bombing and the dramatic papal changeover at the Vatican, according to The Associated Press' annual poll of U.S. editors and news directors.

The saga of "Obamacare" as the Affordable Care Act is widely known received 45 first-place votes out of the 144 ballots cast for the top 10 stories. The marathon bombing received 29 first-place votes and the papal transition 21.

Other strong contenders were the bitter partisan conflict in Congress and the leaks about National Security Agency surveillance by former NSA analyst Edward Snowden.

Last year, the top story was the massacre of 26 children and staff at an elementary school in Newtown, Conn. That result came after a rare decision by the AP to re-conduct the voting; the initial round of balloting had ended Dec. 13, a day before the Newtown shooting, with the 2012 election at the top.

The first AP top-stories poll was conducted in 1936, when editors chose the abdication of Britain's King Edward VIII.

Here are 2013's top 10 stories, in order:

HEALTH CARE OVERHAUL: The White House had hoped the Oct. 1 launch of open enrollment would be a showcase for the upside of Obama's much-debated overhaul. Instead, the website became a symbol of dysfunction, providing Republicans and late-night comics with ammunition, and worrying the president's Democratic allies. The site gradually improved, but a wave of cancellation notices from insurers undercut Obama's oft-repeated promise that people who liked their existing coverage could keep it.

BOSTON MARATHON BOMBING: In seconds, a scene of celebration transformed into one of carnage, as two bombs exploded near the finish line of the Boston Marathon in April. Three people were killed and more than 260 injured, including at least 16 who lost limbs. Authorities soon identified two suspects 26-year-old Tamerlan Tsarnaev, who died in a shootout with police, and his brother, Dzhokhar, 20, who faces multiple charges, including 17 that carry a possible death penalty. Though jolted by the bombings and a subsequent lockdown, the city rallied under the slogan "Boston Strong."

VATICAN CHANGEOVER: Pope Benedict XVI stunned Catholics around the world with his announcement in February that he would resign. The cardinal elected to succeed him, soon known as Pope Francis, proceeded to captivate many Catholics and non-Catholics alike with a new tone of openness, modesty and tolerance. Without challenging core church doctrine, he suggested it was time to rethink policy on divorce, focus more on serving the poor, and devote less rhetoric to condemnations of gay marriage and abortion.

DIVIDED CONGRESS: Opinion polls showed Congress with historically low approval ratings, and the key reason was seemingly intractable partisan conflict. Among the consequences were the harsh automatic spending curbs known as sequestration, the partial shutdown of the government in October, and bitterness in Senate after the Democrats used their majority to reduce the Republicans' ability to stall presidential nominations via filibusters.

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AP Poll: Obama Health Care Overhaul Top 2013 Story