ANKARA, Turkey (AP) — Turkey's parliament on Saturday approved a contentious constitutional reform package, paving the way for a referendum on a presidential system that would greatly expand the powers of President Recep Tayyip Erdogan's office.

The decision marks a victory for Erdogan, a polarizing but overall popular figure, who critics view as increasingly autocratic.

In an all-night session that ended early Saturday, lawmakers voted in favor of a set of amendments presented by the ruling party, founded by Erdogan. The reform bill cleared the minimum threshold necessary to put the measures to a national referendum for final approval.

The vote took place with 488 lawmakers in the 550-seat assembly in attendance. A total of 339 parliamentarians voted yes, 142 no, five cast empty ballots and two were ruled out as invalid.

Prime Minister Binali Yildirim celebrated the result saying the decision was now in the hands of the Turkish people who would make the right choice.

"Don't you ever doubt that the people will most certainly make the best decision regarding the constitutional reforms," he told lawmakers. "Our people will head to the polls, will vote with their hearts and minds and make the best choice for Turkey."

A public vote on the issue is expected as early as March 26, and no later than mid-April, according to officials of the ruling Justice and Development Party, or AKP.

In addition to changing the system of government, the reform bill would allow the president to keep ties with his party and restructure the nation's highest judicial body.

It increases the number of seats in the assembly to 600, lowers the minimum age of lawmakers to 18 and foresees simultaneous parliamentary and presidential elections every five years.

Ruling party officials argue a strong presidency is needed for a strong Turkey capable of surmounting a broad array of internal and external security threats.

Opposition lawmakers see the changes as a bid to cement the powers of Erdogan, who has established a de-facto presidential system since coming into the office in 2014. Some complained that restrictions on the press and intense pressure to toe the line had left no space for them to air their views.

Kemal Kilicdaroglu, head of the opposition Republican People's Party, condemned the outcome saying parliament had "handed over its own authority" and "betrayed" its history. He vowed to lead a "struggle for democracy" to have the reforms rejected in the referendum.

Saturday's decision concludes almost two weeks of heated debates in the assembly, where lawmakers traded barbs and came to blows on more than one occasion.

The parliamentary vote comes six months after a violent attempt to unseat the Turkish president failed and ended with the masses rallying to defend him.

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Soguel reported from Basel, Switzerland. Cinar Kiper in Istanbul also contributed.