ISTANBUL — Jailed militant leader Abdullah Ocalan has called on the main pro-Kurdish political party to remain “neutral” in Istanbul’s mayoral election in what was widely seen as an entreaty to abandon its support for the opposition candidate and help President Recep Tayyip Erdogan’s party retain control of the city.

But the left-wing Peoples’ Democratic Party (HDP) signaled it would continue to back Ekrem Imamoglu, who narrowly won the mayorship March 31 before electoral officials agreed with his opponent’s claims that technical irregularities required a do-over vote, scheduled for Sunday.

The surprise entry of Ocalan into the battle for Istanbul illustrates how crucial the HDP’s estimated 1.2 million voters are to the election’s outcome. Imamoglu, from the Republican People’s Party (CHP), credited Kurds for helping him narrowly beat his rival, Binali Yildirim of the Justice and Development Party (AKP), the first time.

In a series of tweets, the state-run Anadolu news agency late Thursday quoted from a purported statement from Ocalan calling on the HDP to sit out the vote. Ocalan, reviled by most Turks for leading the armed Kurdistan Workers Party (PKK) until his capture in 1999, has been banished from the public sphere for years.