“I have always felt that I had a special relationship with the Irish people,” Mr Duffy told The Irish News on Thursday.
“I think it was that shared affection for our country that made me the best politician in the world.”
Mr Duffy was a political pioneer who sought to win over a generation of voters in his quest to wrest power from the Democratic Unionist Party.
His victory in the 2014 General Election marked a turning point in his political career and was seen as a major blow to the DUP.
“Joe’s legacy is what’s gone on in the last 20 years and I’m glad to be able to see it through,” said Mr Duffy.
Mr Duffy’s resignation as leader of the Fine Gael party is seen as the culmination of his campaign to leave the Dáil and to lead his party into government in a new, pro-business coalition with Fine Gael.