ISTANBUL (AP) — The leader of Turkey's main opposition party said Friday he believes he has become the voice of thousands of people victimized by the government's large-scale crackdown on civil servants, journalists and critics following last year's failed coup attempt.

Republican People's Party leader Kemal Kilicdaroglu is leading a 426-kilometer (250-mile) "March for Justice" from the capital of Ankara to Istanbul to protest President Recep Tayyip Erdogan's policies.

The march, now in its 23rd day, originally was planned to denounce the imprisonment of a party lawmaker. It has grown into a wider protest of the post-coup crackdown that has extended beyond people associated with the coup to include journalists, academics and Kurdish politicians.

Tens of thousands are marching alongside Kilicdaroglu.

"There are many victims in this society, and we have become their spokesman," he told The Associated Press on Friday.

"If only there was no need for this march and there was democracy, media freedoms, if civic society groups could freely express their opinions," the opposition leader added.

The government says the crackdown is necessary due to the gravity of the July 2016 coup attempt, in which state buildings were attacked with helicopters and tanks and more than 240 people died.

It says the threat posed by a network of followers of U.S.-based Muslim cleric Fethullah Gulen — whom Turkey accuses of masterminding the coup — is not yet over. Gulen has denied involvement.

The government has accused Kilicdaroglu of supporting terrorist groups through his protest action.

The march ends Sunday with a rally planned near the prison where the Republican People's Party legislator is being held.

Parliament member Enis Berberoglu was sentenced to 25 years in prison for revealing state secrets for allegedly leaking information to an opposition newspaper suggesting that Turkey's intelligence service had smuggled weapons to Islamist rebels in Syria.