MADRID — Adolfo Suarez, Spain’s first democratically elected prime minister after decades of right-wing rule under Gen. Francisco Franco, has died aged 81.

Suarez died Sunday afternoon in Madrid’s Cemtro Clinic hospital, family spokesman Fermin Urbiola said. Suarez had been suffering from Alzheimer’s disease for a decade. The cause of death was “chronic obstructive pulmonary disease made worse within the context of Alzheimer’s disease,” said Dr. Isabel de la Azuela of Cemtro.

Suarez had been admitted to the hospital Monday with pneumonia. On Friday, his son Adolfo said his condition had deteriorated and that he was expected to die within days.

Suarez became secretary-general of the National Movement, which was Spain’s only party during Franco’s rule, and also was director-general of state television broadcaster TVE.

He was 43 when he was chosen in 1976 by King Juan Carlos to lead the country toward a democratic parliamentary monarchy after Franco’s death a year earlier. Suarez had the king’s trust and the two were close.

Under Suarez’s leadership the new Parliament approved a democratic constitution in 1978, a milestone that proved popular enough to enable him and his party to win re-election the following year. During his time in office, Suarez surprised his critics by legalizing political parties and trade unions and calling for an amnesty for political offenses, steps that were seen as decisive after Franco’s 1939-1975 authoritarian rule.