"We will submit our proposal for constitutional reform to the Turkish national assembly next week," Yildirim told journalists in Ankara.

The ruling Justice and Development Party (AKP), co-founded by Erdogan, proposes to change Turkey's parliamentary system into a presidency, like that of France or the United States.

The country is also still reeling from a failed July 15 coup blamed on the US-based Islamic preacher Fethullah Gulen that has been followed by a relentless purge of his alleged supporters from all state institutions.

Yildirim said any changes would be put to the people in a referendum in "early summer" if "everything goes well" and it is approved by the parliament.

During his time as president, he has transformed what was usually a more ceremonial post, concentrating powers in what opponents have said is a violation of the existing constitution.

Officials often say the bill, which would change the constitution, would legalise what has become a de facto situation.

For the bill to pass, it needs 330 votes from the 550-seat assembly to put any changes to the constitution -- which dates back to the 1980s -- to a public vote.

While a super-majority of 367 votes are needed to approve the changes without public consultation, the government has repeatedly said that even if it were to get that number, they would hold a referendum.

The AKP currently falls below the number needed to go to a referendum, with only 317 seats including the speaker Ismail Kahraman.

To make up its shortfall, it has been chasing the support of the fourth-largest Nationalist Movement Party (MHP), which has 40 MPs in the assembly.

The main opposition Republican People's Party (CHP) and the pro-Kurdish Peoples' Democratic Party (HDP) have repeatedly said they would oppose the reforms but MHP support would be enough to go to a vote.

Yildirim made his remarks during a press conference with MHP leader Devlet Bahceli after the two men met to discuss the changes.

Bahceli told reporters that the 90-minute meeting had gone "positively", suggesting the MHP could give its support and enough votes for the bill to pass.

"This proposal will surely be a text that has been agreed with or negotiated and then come to be agreed on with the MHP," Yildirim added.