Elections are expected to be the Turkish opposition’s best chance to unseat President Recep Tayyip Erdogan in 20 years.

“Our nation will go to the polls to elect its president and parliamentarians on May 14,” Erdogan said in a speech on Friday after signing the election decision.

The announcement was expected with Erdogan saying in a speech last week the Turkish nation would do “what is necessary” on the date now officially announced as election day.

The elections could be the country’s most significant vote in decades, with Erdogan’s two-decade rule of Turkey at risk.

The opposition has united around Kemal Kilicdaroglu, the leader of the second-biggest party in parliament, the Republican People’s Party (CHP).

However, another prominent opposition leader, Meral Aksener, initially opposed Kilicdaroglu’s candidacy as prime minister, voicing her doubts last week as to whether the former bureaucrat, regarded by some as uncharismatic, could beat Erdogan.

On Monday, Aksener announced her support for Kilicdaroglu.

Erdogan, whose popularity has waned as Turkey’s economic crisis continues, has been accused of authoritarianism by his opponents.

His government’s response to February’s devastating earthquakes in the southeast of Turkey, which killed more than 46,000 people and left hundreds of thousands living in tents or temporary accommodation, has also been criticised, although Erdogan has defended the government’s actions.

Erdogan, who has been Turkey’s leader since 2003, and has occupied the presidency since 2014, still retains significant support, and could yet emerge on top, alongside his AK Party.