By Daren Butler and Ayla Jean Yackley
ISTANBUL (Reuters) - President Tayyip Erdogan sought a crushing victory for his vision of a "new Turkey" at parliamentary elections on Sunday, a vote that could furnish the country's most divisive modern leader with sweeping executive powers.
The mood was tense at some polling stations, particularly in the mainly Kurdish southeast, after a bombing on Friday killed two people and wounded at least 200 at a rally for the pro-Kurdish Peoples' Democratic Party (HDP).
The attack has sharpened attention on the HDP, which is looking to enter parliament for the first time as a party. Its success could put an end to 12 years of single-party rule by the AK Party Erdogan founded.
Erdogan hopes the AKP can win a resounding majority to change the constitution and create a U.S.-style executive presidency. Opponents say his vision would lack necessary checks and balances from other branches of state.
"They say 'If Erdogan gets what he wants on Sunday he will be unstoppable'," Erdogan told a rally in the northeastern province of Ardahan on Saturday.
"They actually mean Turkey will be unstoppable."
While the AKP is expected to again be by far the largest party, it may be unable to secure an outright majority if the HDP crosses the 10 percent threshold to enter parliament. The HDP has widened its appeal beyond its Kurdish core vote to centre-left and secularist elements disillusioned with Erdogan.
"I am certain the HDP will exceed the threshold. My only worry is the theft of votes," said Bahar Haram, a 25-year-old social services worker voting in Diyarbakir, the biggest city in the southeast, where the HDP draws most of its support.
Like many people in the region, Haram said her priority was ending conflict between Ankara and the rebel Kurdistan Workers Party (PKK), which took up arms in 1984 in an insurgency that has killed 40,000 people.
Ankara launched peace talks with the PKK more than two years ago. The HDP's presence in parliament could be crucial to pushing that process forward.
"God willing, our nation's decision this evening will confirm the strength of our democracy," Erdogan told reporters after voting on the Asian side of Istanbul.
He also said he believed turn-out was strong, something that if borne out could favour AKP.
Erdogan wants the AKP to secure 400 of 550 seats, a supermajority which looks unlikely. At the last parliamentary election in 2011, the party won 49.8 percent of the vote.
Polling ended at 1400 GMT. First results were due at 1800 GMT although authorities could lift a reporting ban before then.
"STABILITY OR CRISIS"
While constitutionally required as president to stay above party politics, Erdogan has held rallies throughout a confrontational campaign, joining Prime Minister Ahmet Davutoglu in attacking opposition parties.
The two have portrayed the election as a choice between a "new Turkey" or a return to a history marked by short-lived coalition governments, economic instability and coups by a military whose influence Erdogan has now reined in.
HDP leader Selahattin Demirtas, voting in Istanbul, saw abuse of electoral process. "The election campaign did not happen in the framework of a just and fair contest."
Erdogan has championed religious conservatives who he says were treated as second-class citizens over decades of secularist rule. He cultivates an image of Turkey that draws more on its Ottoman history and culture, orienting it to the Middle East rather than the West.
The message resonates with voters in Turkey's Anatolian heartland, including the city of Konya where Davutoglu voted.
"I voted for the AK Party and for Davutoglu. He's an honest man, a good Muslim, he prays five times a day, and he's from Konya like us," said 59-year-old Ekrem Bal, twirling prayer beads as he stood outside a polling station.
But Erdogan may lose votes of some Turks, especially the secularly minded, perturbed by his increasingly religious, and combative, tone. Others impressed by democratic reforms in his first two terms of government may now be disenchanted by a clampdown on the media and apparent intolerance of criticism.
Some conservatives see him as too conciliatory towards the Kurds. The PKK is designated a terrorist organisation by the United States and EU as well as Turkey.
"I am worried. I don't want the HDP to cross the threshold because of their links with terrorists," said 45-year-old Tahsin Karaman, a night security guard, voting in Istanbul.
"I used to support the AK Party but this time I am voting for the MHP. It's a warning vote," he said, referring to the rightist Nationalist Movement Party (MHP).
(Additional reporting by Humeyra Pamuk in Diyarbakir and Jonny Hogg and Tuvan Gumrukcu in Konya; Writing by Daren Butler and David Dolan; Editing by Ralph Boulton and Nick Tattersall)
