The ruling Justice and Development party has failed in the past to secure enough parliamentary support for a change to the presidential system
Turkey's ruling AKP on Saturday submitted to parliament a package of constitutional reform proposals that would expand the president's powers, party officials said, in a move that could potentially see President Recep Tayyip Erdogan govern until 2029.
The package would also bring structural changes to Turkey's security and judiciary, while implementing criminal liability for the president, who previously was immune from all crimes except treason.
The AKP, unable to legalise the changes on its own, has been meeting with the Nationalist Movement Party (MHP) in order to introduce an executive presidential system long sought by Erdogan and his supporters.
Deputy Prime Minister Nurettin Canikli told A Haber television in an interview on Friday that parliamentary and presidential polls would be held in 2019, cementing a radical change in power structures.
"The referendum looks like it could be held around March or April, but it could also be pushed to May," Canikli said, ruling out any early election before 2019.
A senior official from the ruling AKP, in power since 2002, said the party would submit its proposal on the constitutional changes to parliament on Saturday.
Erdogan has turned a largely ceremonial presidency into a powerful platform at a time of domestic upheaval by drawing on his own unrivalled popularity. The AKP now seeks a strong executive presidency that, while formalising his personal powers, could avert any relapse into the fractious coalition governments of the 1990s.
AKP officials refer to the current system as a "de facto presidential system".
Opponents, however, fear the change will bring increasing authoritarianism to a country already criticised by Western allies over its record on rights and freedoms, especially after purges following the coup attempt.
Canikli said he expected all members of the AKP to vote in favour of the proposal and that the nationalist MHP opposition would also support the bill.
"The leaders of the AKP and MHP are in agreement at the moment, the following period is one for the commission and general assembly," Erdogan told reporters after Friday prayers.
Any constitutional change needs the support of at least 330 deputies in Turkey's 550-seat assembly to go to a referendum. The AKP has 316 lawmakers eligible for voting, and the MHP 39.