The opposition alliance in Turkey will announce today that its candidate to face President Recep Tayyip Erdogan in the May elections will be Kemal Kilicdaroglu.

The choice of the leader of the Republican People’s Party (CHP), however, caused a rift in its ranks. One of its main parties rejected the candidacy of Mr. Kilicdaroglu.

Meral Aksener, the head of the nationalist Good Party (İYİ), the second-strongest in the alliance, made it clear on Friday that she would not be in favor of this candidacy and would leave the six-party coalition.

In Ms. Aksener’s view, Mr. Kilicdaroglu, 74, has little chance of winning. He suggested naming either Ekrem Imamoglu, the popular mayor of Istanbul, or Mansur Yavas, the mayor of Ankara, as a common candidate. Both of these CHP politicians are doing better in the polls than the party leader.

But the long-time leader of Turkey’s main opposition was supported by his own party and the four smaller parties in the coalition. The two mayors also spoke in favor of him.

The opposition’s chances of beating Mr. Erdogan in presidential and parliamentary elections on May 14 are being hit by the split, observers say.

Critics of the head of state hoped the motley alliance would stay together.

When she presented her positions in January, she promised that the country would return to the parliamentary system, that the presidential system would be abolished, thanks to which Mr. Erdogan — the master of the game in Turkish politics for the past 20 years — had amassed too much power. in his hands since 2018.

The alliance promised to re-ceremonialize the office of the president, stripping the holder of the right to issue executive orders, stipulating that he should not belong to any political party and stipulating that his term of office would be seven years.

He also pledged to take steps to reduce soaring inflation to single digits within two years, restore the independence of Turkey’s central bank and revive Turkey’s decades-stalled bid to join the European Union.