Éamon Ó Cuív has been made deputy leader of Fianna Fáil, following the recent death of Brian Lenihan.
Michael McGrath will now be the party’s finance spokesperson.
Commenting on the appointment, Mr McGrath said: 'It is a particular privilege for me to succeed the late Brian Lenihan in this role. Brian was a great colleague and friend, and I learned a great deal from him.'
'It is not possible for anyone to fill his shoes, but I will fulfil the role to the best of my ability.'
Former finance minister Brian Lenihan died on 10 June aged 52. He was diagnosed with pancreatic cancer in December 2009.