Armenia's new President Armen Sarkisian was sworn in on Monday but power is expected to remain with his predecessor, who will likely become premier as the ex-Soviet republic shifts to a parliamentary form of government.
The former ambassador to the United Kingdom took the oath of office as president at an extraordinary parliamentary session, placing his right hand on a 7th-century manuscript of the New Testament, and the Armenian Constitution.
The 64-year-old then received blessings from the head of the Armenian Church, Catholicos Garegin II.
"We must consistently fight against corruption and social injustice," he told lawmakers. "We will succeed if we rally round this goal and work together - instead of drawing dividing lines."
Sarkisian's inauguration allows controversial 2015 constitutional amendments to come into force, turning the country into a parliamentary republic with a strong prime minister.
The political shift was initiated by the outgoing president Serzh Sarkisian - who is no relation to the new leader - and was approved in a referendum with 63 percent of the voters backing the changes.
Critics of pro-Moscow Serzh Sarkisian, 63, say the reforms have been designed to increase his power in a new capacity as premier.
He has already served as premier in 2007-2008 and so far has not explicitly confirmed that he will seek to become prime minister again. The ruling party has defended the constitutional reform as a move aimed at consolidating the Caucasus nation's democracy and improving the balance of power between the legislative and executive branches.
But the opposition has complained of widespread violations at polling stations during the December 2015 referendum, prompting thousands to rally in protest.
Council of Europe observers have said the referendum was marred by allegations of large-scale vote buying and multiple voting, among other irregularities.
Meanwhile, Serzh Sarkisian's plans for the future have become the main intrigue of Armenian politics.