The result is, admits Peoples' Democratic Party (HDP) leader Selahattin Demirtas, balanced on a "knife-edge". But the rise of his pro-Kurdish party means it could play the decisive role in determining the outcome of Turkey's legislative elections.

All predictions forecast that the HDP will come fourth in the elections Sunday with just below or above 10 percent of the vote.

But the 10 percent figure is the dividing line between triumph and wipe-out. Only if a party polls above this figure can it send MPs to the Turkish parliament, in a notoriously strict threshold rule.

Should the HDP win more than 10 percent, it could stymie the ruling Justice and Development Party's (AKP) dream of changing the constitution to give President Recep Tayyip Erdogan more power, and may even force it to form a coalition.

The HDP's trump card is Demirtas, 42, nicknamed the "Kurdish Obama". He is the only Turkish politician to rival Erdogan's rhetorical skills, and also boasts a fine singing voice and talents on the baglama (Turkish lute).

"We will clear the threshold and achieve strong presence in the parliament... There's no option for us to remain outside," Demirtas said after a rally in the southeastern province of Mardin near the Syrian border.

While the party's stronghold is still in the Kurdish-majority southeast, Demirtas said the key was to win extra votes in the Aegean Sea region dominated by secular Turks who despise the Islamic-rooted rule of the AKP.

"I am sure we'll pass the threshold with the votes we will receive from the west," he said.

- 'A party of all' -

Under Demirtas, the HDP has sought to broaden its appeal beyond Kurds, who make up around 20 percent of Turkey's population and many of whom are AKP supporters.

With its leftist economic policies, some compare the HDP to the radical anti-austerity coalition Syriza in Greece, which symbolised the return of the left in Europe.

The only Turkish party with a strong emphasis on women's and gay rights, the HDP says it is reaching out to every segment of Turkish society.

"We are a party of all. We are a party of all oppressed," Demirtas said.

"We will garner votes from all over Turkey," he said.

Uniquely in Turkey, under HDP rules, a man and a woman must share the chairpersonship and Demirtas' co-chief is Figen Yuksekdag. The party also considers itself a champion of Turkey's small but historically important Christian minorities.

"We oppose any move to use religion as a political tool. The HDP is the guarantee of democratic secularism that cherishes freedoms," said the HDP's candidate from Mardin, Erol Dora, a Syriac Christian who is seeking a second term in parliament.

- 'Stop the AKP' -

But Demirtas has taken a huge gamble by fielding candidates as a party and risks having zero MPs if the HDP fails to clear the threshold.

In the past, pro-Kurdish politicians ran as individuals on independent tickets and the HDP had 29 MPs in the outgoing 550-seat parliament.

Erdogan and the AKP have fired multiple salvos at the HDP in recent weeks, with such aggression that one could think it was the main opposition party.

The AKP argues it is already giving Kurds greater rights and working for a peace deal to end the decades-long insurgency by the Kurdistan Workers' Party (PKK).

The president has sought to accuse the HDP of being anti-Islam, as the party has promised to abolish Turkey's top religious authority Diyanet and mandatory religious courses. He has even claimed it is a front for the PKK.

Many Turks would be happy to see the HDP in parliament as they believe the party may put a brake on Erdogan's ambitions to grab greater powers.

"I believe the HDP will make its way to the parliament because it is western Turkey's only tool to stop the AKP," said Abdullah Demir, a hotel owner.

Fazil Say, a renowned Turkish concert pianist and a strong opponent of the AKP, wrote in an opinion piece that he would vote for the main opposition Republican People's Party (CHP) but said the HDP must be in the parliament.

"Would it be better if the AKP comes to power with 360 seats and does whatever it wants?" he wrote.

Efforts to make peace with the PKK have stalled in recent months and could hit further trouble if the AKP has to make a coalition with the Nationalist Movement Party (MHP).

Apparently courting the nationalist vote, Erdogan had enraged Kurds earlier this year when he denied that there was a "Kurdish problem" in Turkey.

"Kurdish people no longer have faith in election-oriented policies aimed at saving the day and instead expect concrete steps," said Emin Irmak, the HDP's mayor in the Artuklu district of Mardin.