President Barack Obama played the Guinness card again on St Patrick’s Day as he joined his Irish cousins for a pint of the black stuff in a Washington bar.

Revelers at The Dubliner pub, near the city’s iconic Union Station, were flabbergasted when the President’s motorcade drew up and he alighted with his Irish guests from his ancestral homeland of Moneygall.

Downing a pint of Guinness to chants of ‘Four More Years,' President Obama was more than happy to be Irish for the day ahead of Tuesday’s official state reception for Ireland’s Prime Minister Enda Kenny.

He was accompanied by publican Ollie Hayes, owner of the bar that hosted the US leader last summer, for another pint of plain, and cousin Henry Healy, from the small village of Moneygall in Tipperary that was home to his ancestors.

Some Dubliner regulars had queued from 10 am for his lunchtime arrival and cheered as he got out of his car wearing a moss green jacket and a pin badge that read VIP Guest.

Shaking hands as he made his entrance, President Obama passed the sign with the pub’s motto - “He who drinks and knows his pace is always welcome in this place. But he who drinks more than his share is never welcome anywhere.”

It’s unclear as to whether or not President Obama paid the $10 cover charge but he did pose for photos with 21-month-old Danny Cooper Coleman.

“Hey, Danny, who’s this?” Obama asked, holding out his VIP GUEST button, which bore the child’s image and the words ‘Tell ‘em Danny sent you.'

Asked how the President enjoyed his Guinness, the baby’s grandfather Danny Coleman said: “He finished it!”

Bartender Brian Keane also confirmed to reporters that he had received just five minutes notice that the President was on his way.

Chicago native Adam Joseph, now resident in DC, said: “I told him ‘Mister President, it’s my birthday!’ And he said ‘Happy birthday.’”

As he left the pub, President Obama had a message for the Irish revelers in for the day.  “I expect you guys,” he said, “to behave yourselves.”