Kemal Kilicdaroglu, leader of Turkey's main opposition Republican People's Party (CHP), arrives at a nomads congress near the southern town of Silifke in Mersin province, Turkey April 22, 2018. REUTERS/Osman Orsal

ANKARA (Reuters) - Turkey’s main opposition Republican People’s Party (CHP) and three other opposition parties have reached a deal on an alliance for snap parliamentary elections on June 24, a CHP official said on Wednesday.

The official, who declined to be identified, told Reuters the deal between the CHP, the fledgling Iyi (Good) Party, the Islamist Saadet Party and the Democrat Party would be formally announced at a news conference on Thursday.

It will enable the smaller parties in the alliance to skirt a regulation that mandates parties must receive at least 10 percent of the vote to enter parliament. The deal creates a broad coalition against President Tayyip Erdogan’s ruling alliance.

Erdogan’s ruling AK Party has established an alliance with the Nationalist Movement Party (MHP).

Broadcaster NTV said the opposition alliance deal would be signed at 3 pm (1200 GMT) on Thursday. A deadline of May 6 was set for election alliances to be filed with the High Election Board.

Erdogan has won nearly a dozen elections and dominated Turkish politics since his Islamist-rooted AK party first swept to power in 2002. The elections will mark Turkey’s transition to a presidency with new sweeping executive powers, agreed under a narrowly approved referendum last year.