Ericq Pierre got the support of the Senate last week
The parliament of Haiti has rejected the president's choice for a new prime minister, prolonging the country's period without a government.
The nominee, Ericq Pierre - an international banker - lost a vote of approval by 51 to 35.
Last month the former Prime Minister Jacques-Edouard Alexis was dismissed for failing to manage the economy of the desperately poor country.
Riots over high food and fuel prices in April left at least six people dead.
Mr Pierre - an official with the Inter-American Development Bank - had been approved by the Senate last week, but was rejected by the lower house.
An opposition MP, Levaillant Louis Jeune, said they did not have faith in his political leadership.
"We didn't really believe in the plan that he had for the people of this country," Mr Jeune told journalists.
Mr Pierre had also been rejected by the lower house for the same position in 1997.
Haitians protested against high food prices in April
President Rene Preval will now have to nominate another candidate.
The previous prime minister, Jacques-Edouard Alexis, was sacked following widespread rioting over soaring food prices.
Senators said he had not done enough to increase national food production and lower the cost of living.
Haiti is one of the poorest countries in the world.
Most Haitians earn no more than $2 a day, and they have struggled to feed themselves as the prices of rice, beans and fruit have risen by 50% in the last year.