Istanbul, Turkey – In the run-up to Turkey’s key parliamentary and presidential elections, the Kurdish vote is seen by many as one of the major factors that could determine the outcome.

For the first time, voters in Turkey will cast ballots on Sunday in simultaneous presidential and parliamentary polls. The process is in line with last year’s constitutional changes that will transform the country’s parliamentary system to an executive presidential one by granting the top office increased powers.

In the past, Kurdish votes were distributed between the ruling Justice and Development Party (AK Party) and Turkey’s left-wing pro-Kurdish movement – which was represented by the People’s Democratic Party (HDP) in the two most recent polls.

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Turkey election: All you need to know about the June 24 polls

The HDP’s presidential candidate is its imprisoned former leader Selahattin Demirtas, who successfully brought his party into mainstream politics in the mid-2010s by attracting young, liberal voters.

Demirtas, along with several other former HDP members of parliament, has been in jail since November 2016, accused of having links to the outlawed Kurdistan Workers Party (PKK). His trial began in December last year and, if convicted, he faces up to 142 years in prison. Demirtas denies the charges.

With the HDP’s campaign virtually absent in mainstream media’s election coverage, Demirtas relies on social media and his lawyers, who regularly visit him in prison in the northwestern province of Edirne, to get his message out.

On June 17, he appeared on television for the first time since his arrest.

“The only reason I am here is because the AK Party is scared of me,” Demirtas said in a pre-recorded speech broadcast by state TV from his prison cell, legally granted to all presidential candidates.

HDP vs election threshold

Opinion polls have suggested that President Recep Tayyip Erdogan’s AK Party might not achieve a parliamentary majority if the HDP manages to gain more than 10 percent of votes on Sunday, which is the unusually high threshold required for a party to enter the 600-seat assembly.

Two alliances, the People’s Alliance – Erdogan’s AK Party and the right-wing Nationalist Movement Party (MHP) – and the Nation Alliance – led by centre-left main opposition Republican People’s Party (CHP) and right-wing IYI Party – are expected to enter parliament.

That leaves the HDP in a position to tip the balance of power.

Demirtas has also said that if the presidential race goes to a second round, he would back any candidate running against Erdogan.

The HDP presents itself as a party that advocates democratic rule, human rights and wider political freedoms.

However, Turkey’s conservatives and many seculars living in the west of the country remain sceptical of such claims, and of the party’s denial of links to the PKK, which has waged a decades-long armed fight against the Turkish state that killed tens of thousands of people.

The HDP’s pro-Kurdish predecessors, which were shut down one after the other by the Turkish judiciary in the 1990s and 2000s, had resorted to entering the polls with independent candidates in a bid to get around the high election threshold.

The HDP passed the 10 percent election threshold in the June and November 2015 polls [Cagan Orhon/Al Jazeera]

But in polls in June and November 2015, the HDP entered the race as a political party and its appeal to non-Kurdish voters was wide enough to enable them to exceed the 10 percent mark – an unprecedented result.

The June 2015 vote failed to provide a government after the AK Party lost its majority in parliament for the first time since it was founded in 2001 – an outcome largely attributed to the HDP’s strong performance. Nonetheless, five months later, the AK Party regained the majority to rule again on its own.

‘We represent the whole of Turkey’

Zuheyla Gulum, an HDP parliamentary candidate in Istanbul, said the public’s interest in her party has been on the rise amid concerns of “rising authoritarianism” in the country.

“We represent all parts of the society that is surpassed in this country – from women to minorities, from workers to migrants. We are a party for the whole of Turkey and our diverse list of candidates reflects this fact,” she told Al Jazeera.

“Kurdish votes are important to us, as they are a highly important determinant [for our success]. Turkey’s democracy issues and economic issues cannot be fixed without a lasting resolution to the Kurdish dispute,” Gulum added.

Western governments and human rights groups have condemned the Turkish government’s detentions and purges of tens of thousands of people after a failed coup in July 2016.

Erdogan’s government says the crackdown is within the law and aims to remove coup supporters from state institutions and other parts of society.

Etyen Mahcupyan, a columnist and former adviser to the AK Party leader, said that secular voters might back the HDP at the ballot box to make sure that AK Party loses its majority in parliament – as it did in June 2015.

“We are not talking about very high percentages. The HDP secured 1.5 to two percent of its votes from western provinces in June 2015 elections. The main factor that will determine whether the HDP will be in parliament is still the Kurdish vote,” he told Al Jazeera.

“The CHP voters might act more strategic in the coming polls,” he said, adding that the level of backing the HDP will get from the western provinces depends on how much support voters there think the party needs to get over the threshold.

“There is an increasingly widespread view that the HDP will surpass 10 percent of the votes. And this might decrease the number of the CHP voters changing their votes for the HDP,” said Mahcupyan, who added that Kurds represent about 15 percent of the electorate in Turkey.

Unprecedented success

Still, the AK Party has over the years enjoyed big success against traditionally pro-Kurdish parties in Turkey’s predominantly Kurdish southeast. Until the HDP’s poll showing in 2015, it was also boosted by the fact that previous pro-Kurdish parties entered the elections with independent candidates, which significantly decreased their potential.

During its rule, the Erdogan-led party was also rewarded at the ballot box after introducing reforms that lifted, among others, barriers on Kurdish language teaching and broadcasting.

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Turkey election: All you need to know about the June 24 polls

In 2013, the AK Party launched a peace process with the PKK, despite the risk of upsetting its core conservative voter base. The aim was to disarm the PKK and integrate its members into society.

The process failed in 2015, right after the June polls, and was followed by violent clashes in rural and urban areas in southeast Turkey.

Both sides blamed each other for the outcome. Since then, clashes have broken out in the region, although the situation has been calmer over the past year.

The influence of that violence on the Kurdish electorate is yet to be seen, but Gulum claims the AK Party will lose a lot of Kurdish votes because it moved away from the peace process.

“Regardless of the government’s efforts, the wider part of the society does not see us as terrorists because, in the times we are living, anyone who speaks up against this government is deemed as terrorists,” she said, referring to recent statements by AK Party members targeting her party.

‘PKK pressure is lower’

But Yasin Aktay, a senior adviser to Erdogan and an AK Party MP in the southeast province of Siirt, said the situation in the region is much more secure and relaxed compared to four years ago when Turkey last went to the polls.

“There is less armed PKK pressure on the people here for them to vote for the HDP, as a result of the secure environment provided by the government. But the pressure still exits as the armed group is trying to target young generations with its nationalist rhetoric,” he told Al Jazeera from Siirt over the phone.

Kurds with common sense are thankful to the AK Party that the assimilation and denial policies in the country have ended.

YASIN AKTAY, SENIOR ADVISER TO THE PRESIDENT

“The terror group was using corrupted municipalities’ facilities in the region until trustee [caretaker] municipalities took them over. And this, together with the secure environment, allowed us to provide better services for the people,” he said, referring to the mayors who were replaced by trustees after being removed for alleged terror links.

Aktay underlined his view that the people of southeast Turkey still appreciate the unprecedented reforms his party carried out for the Kurdish people.

Erdogan says that no Kurdish citizen was marginalised in Turkey during his time [Reuters]

“The Kurds with common sense are thankful to the AK Party that the assimilation and denial policies in the country have ended. And they can speak and watch television in Kurdish freely,” he said.

Erdogan said in a recent speech in the southeastern city of Van that no Kurdish citizen was marginalised in Turkey during his time.

“We will not allow terrorists, sinners and blood-sucking vampires thirsty for the blood of people here,” Erdogan added, calling Demirtas a terrorist and his party a wing of the PKK.

Follow Umut Uras on Twitter:  Um_uras

Additional reporting by Cagan Orhon