Claiming Irish ancestry is often seen as a vote-winner for ambitious American politicians, but few can match the credentials of US vice-president Joe Biden - who can prove an extensive Irish heritage with all of his mother's family and some of his father's lineage tracing their origins to Ireland.
According to leading Irish American genealogist Megan Smolenyak - who traced Barack Obama's Irish ancestor Falmouth Kearney to Moneygall in Co Offaly - Mr Biden is roughly five-eighths Irish, with ancestral links to both Louth and Mayo which he is visiting today.
"Vice-president Biden's mother Jean was a Finnegan and she can trace her entire family tree to Ireland, with ancestors named Arthurs, Blewitt, Boyle, Roche, Scanlon and Stanton accompanying her Finnegan name," she explained.
According to Ms Smolenyak, “Most of the immigrants in vice-president Biden’s family were born in the early decades of the 19th century and made the journey to America mid-century, so the Famine was undoubtedly a key factor in their departure.
"With a couple of exceptions, they converged immediately on Scranton, Pennsylvania, and by the time the future vice-president joined the family in 1942, they had been settled there for roughly 70 to 90 years," she revealed in a feature she wrote for Irish America magazine in 2013.
Ms Smolenyak revealed Mr Biden's mother Jean was born in 1917 to Ambrose Finnegan and Geraldine Blewitt, with the former tracing his ancestry to Co Louth and the latter tracing hers to Co Mayo.
Mr Biden's great-great-great-grandfather, Edward Blewitt, who had worked for the Ordnance Survey and later on Griffith's Valuation, left the Ballina area with his wife Mary and their eight children, arriving in New York on board The Excelsior on January 28th, 1851.
Ms Smolenyak’s research led her to Kilmoremoy Parish, where she found a baptismal cert of April 1832 for “a Patt Bluett”, born to Edward and Mary, which fits “rather nicely” with the 18-year-old Patrick who arrived in New York in 1851 and was the great-great-grandfather of the vice-president.
A number of the Blewitt men worked as surveyors and although Patrick settled in Scranton, Pennsylvania, his work took him to New Orleans, where Mr Biden's great-grandfather Edward was born in 1859.
Mr Biden's other great-great-grandfather Owen Finnegan was born in Templetown on the Cooley Peninsula in Co Louth in 1814, and he arrived in New York on May 31st, 1849, to be followed by his wife Jane and their children on board a ship called The Marchioness of Bute in 1850.
According to Ms Smolenyak, the Finnegans, including Mr Biden's great-grandfather James, settled in Covert, New York before they moved to nearby Ovid. James lost a brother, Michael, during the American Civil War at Cold Harbor, Virginia, while another brother Stephen was wounded.
"Stephen and two of his brothers went to California, and it was James who stayed the closest to home but, after marrying Catherine Roche in 1866 and living in Rochester, New York, for several years, he moved to Olyphant on the outskirts of Scranton, Pennsylvania," she explained.
Their son, Ambrose Finnegan, became Mr Biden's grandfather. He had a tough start in life when his mother died before he was aged two, and his father died when he was just 10. He was raised by his uncle Peter Roche, who had a sign-making business.
"It was on June 1st, 1909, that the Finnegan and Blewitt families finally linked destinies, when Ambrose Joseph Finnegan married Geraldine Catherine Blewitt and their daughter Jean later married Joseph Biden, and the vice-president was their first child, born on November 20th, 1942."
Ms Smolenyak revealed: "I first began poking into Joe Biden's past before he became vice-president, but I was very touched when he signed a copy of the article with the inscription 'Megan, I truly appreciate what you've done for me. My Mom would be so very proud. Love Ya, Joe Biden'."