Fulmuth Kearney, who is Obama's third great-grandfather, left Moneygall for New York in 1850 to eventually settle in Ohio.
"We've never seen such an interest in any election here ever before," said Henry Healy, who claims to be a distant relation of Hawaiian-born Mr Obama.
Mr Healy, whose family has been in Moneygall since 1750, has traced his family tree to meet the Kearney Obama dynasty.
"In 1760 a Joseph Kearney of the parish of Moneygall married a Sarah Healy also of the parish," he said. "Sarah and Joseph are great-grandparents to Fulmuth Kearney who was Barack's last link to Ireland," said Mr Healy.
Residents of Moneygall, on the N7 Limerick road, are gearing up for a US election party in Ollie Hayes's Bar in the town tomorrow night.