Polling is likely to be held on May 14.
In a ceremony in Ankara on Monday, the six parties presented their joint 240-page program for a post-victory Turkey, but did not name their joint candidate to run against Erdogan.
Erdogan, who has been in office since 2003 — first as prime minister and as president since 2014 — introduced a presidential system in 2018 that abolished the office of the prime minister and concentrated most powers in the hands of the president.
The office of the president had been a largely ceremonial post until then.
The opposition has blamed Turkey’s woes, including an economic downturn and an erosion of rights and freedoms, on Erdogan’s system which they say amounts to a “one-man rule.”
The presidential system was narrowly approved in a 2017 referendum and was installed following elections in 2018.
The six parties -- known as the “Nation Alliance” or the “Table of Six” — have been meeting for the past year to come up with a joint plan to beat Erdogan and chart a return to a more democratic system.
The six parties’ failure to nominate a joint candidate to run against Erdogan has however, led to frustration among opposition supporters.
CHP leader Kemal Kilicdaroglu has suggested he wants to run despite the significant popularity of the mayors of Istanbul and Ankara, who managed to oust Erdogan’s ruling party in local elections in 2019.
The longtime Turkish leader has seen a decline in support due to economic instability and surging inflation but has been engaged in a spending spree, including increases in minimum wages and retirement benefits, to win back votes.
On foreign policy issues, the six parties vowed to “work to complete the accession process” for full membership in the European Union, improve strained ties with the United States “based on mutual trust,” and strive to return to the U.S.-led F-35 fighter jet program.
Turkey was kicked out of the project following the Erdogan government’s purchase of Russian-made missile defense systems.
In addition to Kilicdaroglu’s CHP, the opposition alliance is made of Meral Aksener’s nationalist Good Party; Temel Karamollaoglu’s conservative Felicity Party; Gultekin Uysal’s Democrat Party; The Democracy and Progress Party led by Ali Babacan; and Future Party chaired by Ahmet Davutoglu.
Davutoglu and Babacan were co-founders of Erdogan’s ruling party and served in top positions before breaking away from the movement in criticism of Erdogan’s policies.
Excluded from the alliance is the pro-Kurdish Peoples’ Democratic Party, which is the second largest opposition party.
That party is facing closure following a severe crackdown by the government for alleged links to outlawed Kurdish militant groups.