Tens of thousands of protesters are on their way to Istanbul. The march is a response to President Recep Tayyip Erdogan's ongoing purges following last year's failed coup and was sparked when opposition party MP Enis Berberoglu was sentenced to 25 years in prison. The march kicked off three weeks ago in Turkey's capital Ankara and is headed to the prison in Istanbul where Berberoglu is held.

Leading the way is Kemal Kilicdaroglu (c), head of Turkey's main opposition party, the Republican People's Party (CHP), who has been likened to Indian independence leader Mahatma Gandhi. Kilicdaroglu said there is no other way to denounce ongoing crackdowns and the deterioration of democratic institutions. "We feel like we're marching against a wall, and we're going to demolish it," he told DW.

"It's our obligation to form a coalition against the nation's slide towards fascism," said Tur Yildiz Bicer, CHP deputy for the city of Manisa. "After the referendum, we told ourselves 'No, it's not over' … Now we are seeing that even some AKP supporters are backing our march, and this shows people's minds are changing for the better." Some 20,000 to 40,000 people are out on the streets.

One of the protesters is Vesyel Kilic, 65, from Rize, who said he voted for conservative parties until his son was jailed following last year's coup attempt. "It's been 12 months and he still doesn't have an indictment," Kilic said. "I want justice and I noticed this leftist ideology is close to my own, so I came out to support the march." Protesters here are demanding "rights, law, justice."

While the organizers with CHP said one of their main objectives was to unite opponents of Erdogan's agenda, the task will likely prove difficult as relations between Kemalists and Kurdish groups remain tepid due to the political risks involved in being affiliated with armed Kurdish movements. Above, marchers are shown resting in Tavsancil, Turkey, before continuing to Istanbul.

Protesters were often heckled and insulted by passing vehicles and crowds of Erdogan supporters who had gathered along the highway. "The march is not a fight for justice, it only brings shame to the people who are walking in this heat," said Umut Kaveci, 26, a transportation worker not pictured above. "They are just causing traffic [jams] and no one needs that."

Police presence was heavy throughout the march to deter possible attacks and altercations between groups of contrasting ideologies. For the most part, the protest proceeded smoothly, aside from occasional confrontations like this one, where an officer restrained a teenager and told him, "I've been walking with this march since Ankara and I haven't been aggressive with anyone. Don't test me."

One of Kilicdaroglu's bodyguards gets his feet bandaged after another long day on the road. Blistered, swollen feet are common among marchers, as well as heat strokes. Temperatures surpassed 40 degrees Celsius (104 degrees Fahrenheit) in recent weeks and one protester died after suffering a heart attack during a prolonged uphill climb.

Regardless of the obstacles, demonstrators have followed Kilicdaroglu's lead through Turkey's rough terrain. The march covers up to 20 km (12 miles) per day. By night, protesters either return to their homes or camp out on CHP funded campsites where they are provided with food and rudimentary shelter. Above, an exhausted protester sleeps in a dining tent in Tavsancil, just east of Istanbul.

Husnu Sucu, a 58-year-old retiree, said he remained undeterred after walking more than 120 km in eight days and was camping each night with the protesters. "I am doing this for my grandchildren," Sucu said. "We cannot let the current government continue doing what it wants without doing something about it. It is too dangerous for the future of our country."

A haze of smoke permanently hangs over Turkey’s low-income areas through the cold weather months. It’s the product of coal-fired ovens used to heat haphazardly built houses, known as "gecekondu" meaning "settled over night." Since President Recep Tayyip Erdogan came into power, the nation’s poorest residents have received free coal to stay warm, but the welfare hasn’t always translated into votes.

On Sunday Turks will vote in a referendum on whether to convert their country’s parliamentary system into a presidential one led by Erdogan and his governing Justice Development Party (AKP). While Erdogan has largely expanded social welfare programs and improved living standards for low-income voters, many people in Ankara’s slums remain undecided on how they’ll vote.

"When my husband was unemployed, I was thinking of how we would get coal. Then AKP gave it to us for free, and that’s when I understood this party is with the poor," Emel Yildirim, left, a mother of three, told DW. "Before it was hard to see a doctor. Now hospitals are more open to accepting poor people," she added.

Yildirim, a Kurd, said she’s also concerned about conflicts between the Turkish state and Kurdish militants. "If Erdogan gets a 'Yes' vote, it could get better. He says he’s with peace," Yildirim said. "But if you ask Selahattin Dermitas [the jailed Kurdish opposition leader], he says Erdogan will drown Kurds in their blood … It’s hard to make a decision."

A campaign banner is used as a couch cover in an alleyway, where mixed feelings over Erdogan prevail. Nearby, Ali, 25, who sells liver sandwiches from his family car, said, "On March 15, they gave people here bags of coal. Why would they do this in the spring? Winter is over. It’s obviously for the votes."

Ali said his main concern was government corruption. "I don’t know if there’s a problem with the system or with the people that use the system," he told DW. "I have the same questions about Islam. Is it the religion or the people who use the religion that cause trouble? I sound like a 'No' voter, but I’m still undecided."

Three-year-old Ayse stands in front of her home. Her mother, who didn’t want to be named or photographed, said she would vote 'Yes' simply because her husband was doing so. Yildirim said her husband, a chef, was also voting 'Yes' because, "he believes whatever Erdogan says is right. He doesn’t ask questions or analyze anything. There’s no arguing with him."

Feride Turhan, right, pictured with her husband Mustafa, left, and their two sons in their living room. Feride said she still doesn’t understand what the referendum is about. "I’m not interested in politics, but I watch the news every day and no one has explained what the referendum is," she told DW. "I still don’t know which amendments are being changed."

Like most residents in Ankara’s slums, Mustafa Turhan (not pictured here), who works the night shift at a vegetable and fruit warehouse, cited safety as his main concern. He said the AKP expanded ambulance service to low-income areas in recent years, but gun violence was increasing. "At night, people with ski masks and AK-47s rob people," Turhan said. "Even 10-year-olds have guns sometimes."

Mustafa also said schools weren’t improving in their neighborhood. "We accept the free coal because the state takes our taxes and it’s our way of getting them back," Mustafa told DW. "But we’d prefer if they invested more in schools so my sons could have better opportunities," like his eldest son, Mert, who is struggling to find work.