Can Dundar is the former editor in chief of the leading Turkish newspaper Cumhuriyet. He is now living in exile.

When Kemal Kilicdaroglu was elected as head of Turkey’s leading opposition party in 2010, he quickly earned the nickname of “Gandhi.” The moniker had more to do with his faint physical resemblance to the Indian independence leader than with any similarities in revolutionary credentials or background.

Kilicdaroglu, who long headed Turkey’s Social Security Agency, is a career civil servant who only entered politics after retirement. As leader of the Republican People’s Party (CHP), he has proved to be more of a bureaucrat than a rabble-rouser. Critics assail him for his passivity and his failure to capitalize on the mood of the streets. With Kilicdaroglu as party chief, the social-democratic CHP has not managed to rise above 25 percent of the vote. President Recep Tayyip Erdogan always seems to succeed in keeping the opposition on its back foot.

But now the CHP leader’s patience appears to have run out. On June 14, his deputy, Enis Berberoglu, was sentenced to 25 years in jail on espionage charges. Kilicdaroglu responded rather unexpectedly. He announced that he and his supporters were embarking on a protest march from Ankara to Istanbul, a distance of 280 miles. The whole trip will take just under a month.

Berberoglu, a journalist by profession, has long been a target of Erdogan’s ire. A few years ago, the authorities went after Berberoglu for allegedly providing me and my newspaper with footage documenting the covert shipment of weapons to radical Islamist rebels in Syria by the Turkish National Intelligence Agency. I was sentenced to five years and 10 months for publishing this footage in Cumhuriyet, where I was editor in chief. (I was released based on a ruling of the Constitutional Court and later left the country.)

It is the Turkish equivalent of America’s Iran-Contra Affair. And just like Ronald Reagan back in the 1980s, Erdogan initially denied having anything to do with illegal arms sales, though he soon had little choice but to tacitly acknowledge the veracity of the report. But the resemblance ends there. In the United States, the main perpetrators ultimately faced criminal responsibility. In Turkey, it was the people who exposed the scandal who ended up going to jail.

For Kilicdaroglu, Berberoglu’s arrest was a turning point. He could either stay silent and wait for his turn to be arrested or he could take to the streets and join the active opposition. He chose the latter. “Democracy is slipping away,” he declared. “This is the last straw!” Accompanied by a large crowd, he set off on the long walk to Istanbul on June 15.

Building on the Gandhi analogy, some are already comparing Kilicdaroglu’s protest with the Indian leader’s famous Salt March of 1930, when he and his followers walked 240 miles to the sea coast to protest the British colonial monopoly on the production and sale of salt. Kilicdaroglu and the crowd with him are expected to walk five to six hours a day for the next 28 days, ending their march at the prison where Berberoglu is being held.

According to official figures, the government has investigated 150,000 people since last July, when an attempted coup touched off an extraordinary wave of repression. By now, 50,000 Turks have been arrested, and 70,000 civil servants have been sacked. Almost all have been accused of terrorism or complicity with the coup plotters, but it’s clear that their real “crime” has simply been opposition to the government. Erdogan has even referred to the coup as “a blessing from God” that gave him the chance to punish all his opponents.

Fully half of Turks belong to this opposition, as shown by the constitutional referendum earlier this year. Erdogan staged the vote in order to obtain approval for a raft of changes that would vastly expand his powers as president. Yet 50 percent of those who went to the polls ultimately said “no.”

Nonetheless, that has merely led Erdogan to intensify the crackdown. He has accelerated the wave of arrests, announced the extension of emergency measures and moved to silence the last voices of opposition in the media.

Now everyone is waiting to see how Erdogan will react. So far he’s restricted himself to vague threats of a crackdown on the march. Youth groups that sometimes act as unofficial paramilitaries have vowed to block the marchers when they enter Istanbul.

Gandhi’s Salt March led in the short term to the arrest of 60,000 participants, though the British were later forced to release them all. In Turkey, the number of prisoners has doubled in the past five years. Now there are 200,000 of them, and all 372 prisons in the country are filled to capacity. Rather than slowing down, the government is busily building new jails.

We’ll soon see whether Kilicdaroglu’s march, which is supported by the other leftist parties, will trigger a new wave of arrests or succeed in imposing limits on the government’s campaign of oppression.

As such, this new protest will not only test Erdogan’s power, but it will also define the political future of his main rival.