PRAIA Cape Verde' main opposition Movement for Democracy (MpD) party won parliamentary elections, results showed overnight, taking back power after 15 years.
With almost all votes counted from Sunday's poll, MpD had 53.7 percent, versus 37 percent for the former ruling African Party for the Independence of Cape Verde (PAICV).
The West African archipelago, 570 km (350 miles) off Senegal, has avoided the coups and civil wars plaguing its neighbors on the mainland.
But PAICV has come under attack for running up the public debt on expensive infrastructure projects and failing to tackle rampant youth unemployment.
PAICV has controlled parliament for the past decade and a half, but struggled in municipal elections in 2012.
A presidential election is due to be held later this year though the date has not been fixed.
The former Portuguese colony, which has experienced a tourism boom in recent years, recorded per capita GDP of $3,450 in 2014, among the highest levels in Africa. The half a million people who live on the cluster of 10 volcanic islands enjoy one of the continent's lowest poverty rates.
However, it lies along one of the main cocaine trafficking routes linking South America to Europe and has seen a recent surge in drug-related violence.
(Reporting by Julio Rodrigues; Writing by Edward McAllister)