The Turkish parliament voted by a two-thirds majority Friday in favour of lifting the immunity from prosecution of 138 members of parliament, including nearly all the pro-Kurdish legislators.
The two-thirds majority means the matter can pass as a constitutional amendment, without any need for a referendum, in a victory for President Recep Tayyip Erodgan.
The motion still faces a final approval vote, set for later in the day, and must then be published in the official gazette.
Voting in favour were 373 members of the 550-seat house, while 138 were against, according to the official live feed of parliament. Some members abstained.
The measure is widely seen as targeting the pro-Kurdish Peoples' Democratic Party (HDP), as Erdogan has repeatedly called for lifting the group's immunity and accused its parliamentarians of supporting the banned Kurdistan Workers' Party (PKK).
The HDP has strongly denied these charges and insists Erdogan is waging a "totalitarian attack" against the party, aiming to consolidate his own grip on power.
The chief of the HDP, Selahattin Demirtas, told Cumhuriyet newspaper, an opposition daily, that he believes he could now be placed in custody.
"There's no obstacle to our detention, for Erdogan and the courts. If he gets this chance, he would like to do so, with the help of the judiciary which is in his hands," said Demirtas, one of the 50 members of HDP who will lose their immunity. The party has 59 seats.
Erdogan this week took a separate step forward in ensuring he is the dominant force without rival in Turkish politics, after his ruling Justice and Development Party (AKP) chose a long-time loyalist as its new chief.
Binali Yildirim will be confirmed as the new party leader at a meeting on Sunday, replacing Ahmet Davutoglu. The AKP is touting the new leader as being completely in-line with Erdogan and someone who will implement his plan of action.
Specifically, Erdogan is seeking to change the constitution to empower the presidency, a move critics say will weaken parliament and checks and balances.
The AKP, of which Erdogan is a founder, won 317 seats in the last election. To get the two-thirds majority on the immunity vote, the AKP appears to have relied on hardline Turkish nationalists.
Members of the European Parliament, many of whom accuse Erdogan of authoritarianism, have urged Turkey not to lift the immunities.
The second party to be most affected by the change is the centre-left People's Republic Party, the largest opposition group in parliament. The party's leader, who has often verbally sparred with Erdogan, will lose his privileges against prosecution as well.
A second step in voting is underway to confirm when exactly immunity will be lifted for the legislators, who come from the four parties in parliament and all have police dossiers opened against them.
Both articles of the amendment are then voted on together as a package, finally confirming the change.
Turkey has a history of banning Kurdish members of parliament. Last year, the ceasefire between the state and the PKK collapsed and violence is wrecking the mostly-Kurdish south-east of the country.