The 17-member Council for Justice and Democracy, set up after Wednesday's military coup in Mauritania has named Colonel Ely Ould Mohammed Vall as the new leader.
Will Col Vall become the first Mauritanian leader to give up power at the ballot box?
Until the coup, he had been seen as a close ally of deposed leader President Maaouiya Ould Sid Ahmed Taya.
Col Vall, 55, played a prominent role in the 1984 coup which brought Mr Taya to power.
He had been director of national security since 1987 - an unprecedented length of time in such a senior position in Mauritania's administration.
But he has generally remained in the shadows, preferring to read mystery novels at home than becoming involved in the cut and thrust of Mauritanian politics.
He first came to prominence - and became close to Mr Taya - during the 1970s war, after Spain withdrew from Western Sahara.
Former colleagues say Col Vall is decisive and methodical.
His military junta said it seized power to end Mr Taya's "totalitarian regime".
The coup has been condemned abroad but broadly welcomed at home - there were even celebrations on the street.
But before he took over, the exiled opposition wanted Col Vall to be indicted for crimes against humanity, because of the alleged torture and brutal interrogation techniques used in Mauritanian jails under his command.
The coup was welcomed on the streets of Nouakchott
As well as being a military man, Col Vall is from a powerful family of the Bedan (white Moor) class which has always ruled Mauritania.
But black Africans and the Haratin descendents of slaves were among those who celebrated the coup, hoping he will end what they see as their exclusion from political and economic power.
The opposition have also welcomed the takeover and do not think it is just a palace coup, with a different name at the helm but little other change.
They see him as a "Trojan horse" - a member of the old regime who will provide safe passage to a more democratic and prosperous future.
Based on his past aloofness from the political sphere, they believe his promises to step down after organising elections within two years.
That would make him the first Mauritanian leader to give up power at the ballot box.