The African island chain Sao Tome and Principe is preparing to hold a run-off election after none of 10 candidates won an absolute majority in a presidential vote last month.

The top two finishers, former President Manuel Pinto da Costa and Parliament Speaker Evaristo de Carvalho will face off in the second round Sunday.

Former President Pinto da Costa, who led a one-party socialist state from 1975 until 1990, is the favorite to win Sunday's vote. In addition to his comfortable outcome in the first round, he has earned the backing of most of the eliminated candidates.

The country's election commission said Mr. Pinto da Costa had earned 35 percent in the July 17 vote, while de Carvalho, who is also a former prime minister, captured 21 percent.

The two men are competing to succeed President Fradique de Menezes, who is constitutionally barred from seeking a third term.

The tiny archipelago, located in the Gulf of Guinea, is believed to have significant oil reserves and the potential for a thriving tourism industry, but has faced chronic poverty.