Most candidates for the US Presidency like to boast Irish ancestry to try and get a hold of the Irish Catholic vote which seems not to be insignificant. The link is usually fairly tenuous and diluted by history and also by unlikely ancestral liaisons, and the benefit is two way, because Ireland has become littered with “Heritage Centres” celebrating these presidential connections, hoping no doubt for some kind of fame by association.
Now it seems that history has smiled kindly on Obama in this respect - yes, he's Irish. Church records place Barack Obama's maternal forebears in Moneygall, County Offaly. It seems that back in the 1700s Joseph Kearney, Obama's great-great-great-great grandfather, was a wigmaker to that section of society who could afford it: the Anglo-Irish aristocracy. Bad business decisions, the potato famine and other circumstances forced the family out and they ended up as US citizens.
However Mr O'Bama should be wary of playing on the luxury of an Irish connection to secure the Catholic vote. His ancestors were certainly Irish, but they were PROTESTANT Irish!