DIYARBAKIR, Turkey (Reuters) - Thronged with shoppers and men sipping tea on a warm day in early spring, the main streets of Turkey’s Diyarbakir show few signs of the devastation wrought by months of fighting last year between Kurdish militants and security forces.

People wave Turkey's national flags and a man holds a banner during a rally organised by village guards in Cermik, a town in southeastern province of Diyarbakir, Turkey, March 10, 2017. REUTERS/Umit Bektas

But nearby in Sur, the historic district that saw some of the worst violence, the narrow back alleys simmer with anger. Many residents blame both the state and Kurdistan Workers Party (PKK) militants.

How voters in Sur and across the largely Kurdish southeast view the 33-year-old conflict could shape the outcome of an April referendum intended to give President Tayyip Erdogan sweeping new powers. In a close race, pollsters say Kurdish voters, about a fifth of the electorate, could tip the balance.

One resident, Serkan, gestures toward bombed-out buildings and fields of rubble. “Our homes, our memories and our past have been erased, and both sides are to blame for that,” he says.

A 2-1/2-year ceasefire between the government and the PKK broke down in July 2015, pitching the southeast into the worst violence in decades. During the months of security operations that followed, about 2,000 people were killed and up to a half a million displaced, the United Nations has estimated.

Diyarbakir is seen by many of Turkey’s 15 million Kurds as their cultural capital, and Sur is the warren of streets in its ancient heart, encircled by towering Roman-era basalt walls.

BOMBS AND TRENCHES

When tanks bulldozed their way in to root out PKK militants who had excavated trenches and laid explosives, tens of thousands of residents had to leave.

“They should not have dug trenches and set up barricades and rebelled against the state like that. But then the state responded excessively and burned and destroyed,” said Serkan, declining to give his surname for fear of retribution.

The Islamist Kurdish party he supports, Huda Par, backs “Yes” in the referendum, but Serkan says he’s not sure he can.

Turkey’s main Kurdish-rooted party, the Peoples’ Democratic Party (HDP), says a “Yes” vote will increase the grip on power of an authoritarian leader bent on stifling dissent. Thousands of HDP members, including its leaders, have been jailed on terrorism charges, dealing a major blow to its campaigning abilities.

Erdogan accuses the HDP itself of supporting terrorism. The party denies direct links to the PKK, seen as a terrorist organization by Europe, the United States and Turkey.

Pollsters say about a fifth of Kurds, or 4 percent of the electorate, are undecided about how to vote. Recent national opinion polls are mixed - some putting either camp as high as 57 percent. Most indicate a high level of undecided voters.

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“Whoever can convince the undecided Kurds will come out on top,” said Faruk Acar, president of the polling firm Andy-Ar.

Erdogan and his millions of supporters say Turkey needs a strong presidency to avoid the fragile coalition governments of the past. His critics cite the arrest, dismissal or suspension of more than 100,000 teachers, civil servants, soldiers, judges and journalists in the wake of a failed coup last year as evidence of his authoritarian instincts.

‘YES’ BABY

While the HDP has strong backing in Kurdish areas - taking more than 6 million votes, or 13 percent of the nationwide total, in the June 2015 parliamentary election, and nearly 80 percent of votes in Diyarbakir - Erdogan remains popular among some right-leaning Kurds.

“Kurdish voters are not monolithic and their political loyalties span the ideological spectrum,” said Aaron Stein, a senior fellow at the Atlantic Council think-tank.

In the village of Gecitli, 80 km (50 miles) west of Diyarbakir, Mustafa Celik, 43, has named his newborn girl “Evet” (“Yes”) to show his gratitude to Erdogan for easing or scrapping long-standing cultural restrictions.

“We can now speak Kurdish. There are TV stations in Kurdish,” said the 43-year-old, sitting beside a pink cradle where his daughter lay asleep. “That’s all his doing.”

Erdogan later launched peace talks with the PKK, a first for a Turkish leader. But since the ceasefire collapsed, he has ruled out a return to the negotiating table, saying security forces will “annihilate” militants. That has boosted his support among nationalists, but also some Kurds.

“As long as we have the Turkish flag above us, we need no other flag or state,” said Mehfahir Ogulcum, a Kurdish volunteer village guard drinking tea outside a military post in rural Kulp, 140 km northeast of Diyarbakir.

After the PKK took up arms against the state in 1984, Turkey started hiring villagers in the southeast to fight alongside the army and help it navigate the local terrain, a move that sowed division among Kurds.

‘CONSCIENCE OF THE PEOPLE’

The government for its part has promised to put money into redeveloping the southeast, where the scars of conflict are all too visible.

In most parts of Sur, the curfews have now been lifted, but many homes remain unusable.

In Cizre, a largely Kurdish town bordering Syria, buildings are riddled with bullet holes, their windows shattered.

In the crackdown that followed last year’s failed coup, dozens of Kurdish journalists were detained and numerous Kurdish media outlets shut.

HDP lawmaker Osman Baydemir said this was enough reason to vote “No” in the referendum.

“We trust the conscience of the people,” he said. “The fact that the TV channels are off-limits to us, that our party officials are arrested and our leaders are in jail resonates with our people.”

Some in Diyarbakir accuse the HDP of failing to stand up to the PKK when fighting escalated. Others say it should take a harder line against the government. But frustration with the HDP is unlikely to translate into support for Erdogan.

“Those who leave the HDP do not automatically come to the AK Party,” said Acar, the pollster.

For many Kurds, like Huseyin Calis, whose home of 53 years was destroyed by fighting in Sur, the choice is clear.

“It is mostly the state’s fault,” said the 76-year-old, sitting in the living room of a relative’s flat. “We are heartbroken with the HDP too. But our people still can’t bring themselves to vote ‘Yes’ ... I say ‘No’, until the end.”