Voters in the west African archipelago of Cape Verde are preparing to choose a new president.

Four candidates are vying Sunday to replace President Pedro Pires, who steps down after serving two terms.

Manuel Inocencio Sousa is the official candidate of Mr. Pires' ruling African Party for the Independence of Cape Verde (PAICV). Sousa faces a challenge from former party member, Aristides Lima, who broke away from the PAICV after losing his bid to be the official candidate. Lima is contesting this election as an independent.

Analysts say the split could benefit Jorge Carlos Fonseca, the candidate from Cape Verde's main opposition party, the Movement for Democracy.

The fourth candidate, Joaquim Monteiro, is also running as an independent.

If no candidate wins an absolute majority, a run-off vote will be held between the top two finishers.

Cape Verde's first multi-party elections were in 1991, and since then the two main parties have each held power for about 10 years.

In 2007, the former Portuguese colony became only the second country to be considered sufficiently developed to be removed from the United Nation's list of least developed countries.

A large percentage of the island chain's 1.5 million citizens live outside the country.