A woman puts her hands on the cheeks of US President Barack Obama after he spoke at College Green in Dublin May 23, 2011. [Photo/Agencies]

DUBLIN - He downed a pint of Guinness with a distant cousin and checked out centuries-old parish records tracing his family to Ireland. From the tiny village of Moneygall to a huge, cheering crowd in Dublin, US President Barack Obama opened his four-nation trip through Europe on Monday with an unlikely homecoming far removed from the grinding politics of Washington and the world.

"My name is Barack Obama, of the Moneygall Obamas, and I've come home to find the apostrophe we lost somewhere along the way," a clearly tickled Obama - make that O'Bama - told the overflow throng at Dublin's College Green with his wife, Michelle, right by him. "We feel very much at home."

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Obama's feel-good indulgence in Ireland came at the start of a four-country, six-day trip that is bound to get into stickier matters as he goes. The only hitch on day one was the threat of a volcanic ash cloud from Iceland that led the president to leave Ireland without even a night's stay and land in England on Monday night.

His high point in Ireland was a helicopter jaunt to Moneygall, population 350 give or take it, where the president's great-great-great grandfather, Falmouth Kearney, was born and where thousands congregated to welcome the United States' first black president home. Obama met there with his nearest Irish relative, 26-year-old accountant Henry Healy, and they stopped in at Ollie's Bar for a Guinness.

It was a moment and a pint to savor. To the approval of the pub crowd and people all across Ireland watching on television, Obama downed the full pint in four slurps and came away with a foam mustache.

"The president actually killed his pint! He gets my vote," said Christy O'Sullivan, an Irish government clerical worker taking a long lunch break to watch live TV footage of Obama's visit. "He's the first president I've actually seen drink the black stuff like he's not ashamed of something."

An Irish link is good news for any American politician trying to connect with voters, and particularly for one who's been dogged by questions about whether he was even born in the United States. By some estimates, 35-40 million Americans trace their ancestry to Ireland. While Ireland, population 4.5 million, is a relatively small player on the world stage, this nation roughly the size of West Virginia has been a popular stopping point for modern American presidents ever since John F. Kennedy came in 1963.

For Obama, it was a day reminiscent of the campaign season when candidate Obama was greeted by adoring crowds and the president milked it for all it was worth. He spoke enthusiastically Monday of "the bonds of affection" between the United States and Ireland. "There's always been a little green behind the red, white and blue," he said to cheers in Dublin.

It wasn't until the 2008 presidential campaign that Obama discovered he had Irish roots, when a priest of the local Anglican church, Canon Stephen Neill, located the family's baptismal records and established the connection. Falmouth Kearney, who immigrated to the United States in 1850 at the age of 19, is a great-grandfather of Obama on his Kansas-born mother's side. His father was born in Kenya.

In Moneygall, 14-year-old Grainne Ryan scrawled "Obama" and drew a shamrock on her cheeks with eyeliner. Thirty-one-year-old Tara Morris pronounced herself "star-struck," a sentiment that appeared to be shared by many in a country that could use a boost as it weathers a steep economic downturn after its boom years as the Celtic Tiger.

Michelle Obama, for her part, drank her full half-pint and then got behind the bar herself to serve Moneygall's parish priest, the Rev. Joe Kennedy.

The president said the brew somehow tasted better in Ireland than in America. And, by the same token, the crowds here were by far more enthusiastic than those greeting him back home of late.

After getting to London a night earlier than scheduled and overnighting at the US ambassador's residence, the Obamas will enjoy the rarified pomp of a state dinner and sleepover at Buckingham Palace, with Queen Elizabeth II as host.