The measure was approved late on Wednesday, the state-run Anadolu news agency reported. Discussions and voting on other changes to the election law were due to continue on Thursday.
The legislative changes were put forward by President Recep Tayyip Erdogan's ruling Justice and Development Party (AKP) and its far-right ally the Nationalist Movement Party (MHP) earlier this month.
Opinion polls show public backing for the MHP has dropped to single figures ahead of parliamentary and presidential elections scheduled for June next year. Erdogan is likely to again need the support of the far-right party and its voters to help secure re-election as president and a working majority in parliament.
Turkey’s 10 percent electoral threshold, introduced after a 1980 military coup, is the highest in Europe. The European Union has long called on the country to lower it.
Other legal changes include a measure meaning parliamentarians would win seats at the next election based solely on the vote share of each political party in any given district. The current system distributes parliamentary seats based on the vote share of each election alliance, then divides them up based on the share of each party within an alliance. That allowed small parties to win seats in election districts where they obtained a small share of the vote.
The changes to the election law, consisting of 15 articles, are also designed to prevent deputies from switching between political parties, a tactic previously used by the opposition to overcome the electoral threshold.
The amendments require 12 months to come into force, dampening speculation Erdogan will seek a snap election before 2023. Erdogan must also approve the legal changes before they become law.
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