Parliament will hold a special sitting on Monday to elect the new president.
The opposition's leader Ro Teimumu Kepa says it has tried to follow a process to depoliticise the nomination.
Ro Teimumu says her SODELPA Party chose him after discussions with chiefs as opposed to a process of numbers and voting by politicians.
Ratu Epeli was the defence minister in the post-coup regime of Frank Bainimarama following an unsuccessful bid as leader of the National Alliance to win a seat in the 2006 election.
Ratu Epeli is also a former chairman of the Great Council of Chiefs.
Both he and Ratu Epeli Nailtaikau have been military commanders.