Togolese politician Harry Olympio has announced he will stand for president in next month's election, a move which threatens to split the opposition vote.
Olympio's party was the first to organise protests against Faure
On Monday, an opposition coalition of six parties chose 75-year-old Emmanuel Bob-Akitani as their candidate.
Mr Olympio, 44, says he feels a younger man is needed for change and to stand against the ruling party's candidate.
Faure Gnassingbe was briefly made president by the army last month when his father, Gnassingbe Eyadema, died.
He later agreed to step down and call elections following violent street protests and international pressure.
"The symbol of the Togolese struggle for democratic change is not symbolised by the image of an old man who is not capable of running a hectic race," said Mr Olympio, the leader for the moderate Rally for the Support of Democracy and Development (RSDD).
"The struggle for change is represented by dynamic, youthful leadership."
According to the BBC's Ebow Godwin the capital, Lome, his party was the first to openly organise street protests against the installation of Mr Faure - who is the youngest presidential candidate at 39.
Harry Olympio is the nephew of exiled Forces for Change (UFC) leader Gilchrist Olympio.
Politically the men are poles apart, our correspondent says.
Following My Olympio's announcement, the opposition coalition stood by their choice of Mr Bob-Akitani.
Mr Faure is the youngest presidential candidate
"There is no doubt in the mind of our coalition that he is our official, unique candidate," opposition spokesman Yawovi Agboyibo told reporters.
Mr Bob-Akitani, who is vice-president of the UFC, came second to Mr Eyadema in the 2003 presidential election with 34.1% of the vote and will face the 39-year-old Mr Faure in the 24 April polls.
Gilchrest Olympio, who lives in Paris, is excluded from running because the constitution says candidates must have lived in Togo for at least 12 months before the vote.
After Mr Faure stood down three weeks into his presidency, West African leaders lifted sanctions it had imposed on Togo.
Eyadema died in Febuary aged 69. He had ruled Togo for 38 years.