The Turkish parliament approved a constitutional reform bill overnight including strengthening the powers of the presidency, paving the way for a referendum expected in the spring which could see President Tayyip Erdogan in office until 2029.
Erdogan says the reform will provide stability in the European Union candidate country at a time of turmoil and prevent a return to the fragile coalitions of the past. His opponents fear it will herald increasingly authoritarian rule.
The bill was approved with 339 votes, parliament said on its official Twitter account on Saturday. The legislation needed at least 330 deputies in the 550-member assembly to support it in order to go to a public vote.
"A new door in Turkish history and in the lives of the Turkish people has been cracked open today. With our people's 'yes' vote, this door will be completely opened," Justice Minister Bekir Bozdag wrote on Twitter.
The reform would enable the president to issue decrees, declare emergency rule, appoint ministers and top state officials and dissolve parliament - powers that the two main opposition parties say strip away balances to Erdogan's power.
Erdogan assumed the presidency, a largely ceremonial position, in 2014 after over a decade as prime minister. Since then, pushing his powers to the limit, he has continued to dominate politics by dint of his personal popularity.
Critics accuse him of increasing authoritarianism with the arrests and dismissal of tens of thousands of judges, police, military officers, journalists and academics since a failed military coup in July.
Erdogan and the government say the extent of the crackdown is justified by the nature of the threat to the state from July 15, when rogue soldiers commandeered tanks and fighter jets in a violent bid to seize power.
Turkey has also been hit by a spate of deadly bombings and gun attacks by Islamic State and Kurdish militants over the past year and a half.