Turkish legislators have approved a bill to amend the constitution, paving the way for the trials of several pro-Kurdish and other deputies.
When parliament convened in Ankara, more than two-thirds of the 550-seat assembly voted in favour of the government-backed bill.
It puts 138 policy-makers at risk of prosecution, the vast majority of them from two opposition parties.
The bill needs to be ratified by President Recep Tayyip Erdogan.
The amendment was proposed by the Justice and Development Party after the president accused the pro-Kurdish People's Democratic Party (HDP) of being an arm of the outlawed Kurdish rebels and repeatedly called for their prosecution on terror charges.
Speaking in the Black Sea town of Rize moments ahead of the final round of voting, Mr Erdogan expressed hope for a favourable outcome, saying: "My people don't want to see criminal deputies in parliament."
The decision coincides with a wave of violence in Turkey's south east after the collapse of a more than two-year peace process between the state and the outlawed Kurdistan Worker's Party, or PKK.
The HDP, which backs Kurdish and other minority rights, denies accusations that it is the political arm of the PKK, considered a terrorist group by Ankara and its allies. The party has urged the government to end security operations in the south east and to resume peace efforts.