|Opinion polls suggest Turkey's prime minister, Recep Tayyip Erdogan, is heading for a third straight election win [EPA]
A bitter election campaign is under way in Turkey, coloured by a sex tapes scandal and growing unrest in the Kurdish southeast, which could pave the way for the most radical overhaul to the country's political system in decades.
Incumbent prime minister Recep Tayyip Erdogan's Justice and Development Party (AKP) is expected to sweep to a third consecutive victory in parliamentary elections on June 12, but less clear is whether the quirks of Turkey's electoral system will hand Erdogan a majority large enough to press ahead with his promise to re-write the country's constitution.
Erdogan, bolstered by victory in a referendum last year on an expansive package of constitutional amendments, has pledged to introduce a "constitution of the people", replacing the existing one, drafted in 1982 in the wake of a military coup, with one founded on western democratic values, pluralism and individual freedoms.
But critics, wary of the AKP's Islamist roots, say the project could further undermine Turkey's secular system and even lead to "South American-style authoritarianism".
They also accuse Erdogan of harbouring personal ambitions over his stated desire to replace the existing parliamentary system with a presidential style of government.
"It's almost for sure that we will have a new constitution in the next couple of years," Ali Carkoglu, a professor of political science at Istanbul's Koc University, told Al Jazeera.
"Everything depends on the result of this election. If the AKP wins with enough seats to reshape the constitution, then a great deal of conflict could emerge out of this. These are issues which touch the very foundations of the republic, and the debate now is getting very ugly."
Stability and continuity
Erdogan's centre-right party is running on a platform of stability and continuity, founded on nearly a decade of impressive economic stewardship in a country more commonly associated with hyper-inflation than the hypermarkets, new highways and hospitals now found across Turkey's once under-developed Anatolian heartland.
That has given the AKP a seemingly unassailable platform, according to opinion polls, which suggest the ruling party has the backing of upwards of 45 per cent of Turkey's more than 50 million voters.
But the AKP's ballot box advantage could translate into even greater parliamentary weight if Turkey's floundering ultra-nationalists - the Nationalist Movement Party (MHP) - fail to achieve the 10 per cent share of the national vote required for a party to enter parliament.
The MHP, which currently holds 72 parliamentary seats, looks set to be punished by its traditionally conservative support base after videos posted on the internet purportedly showed several senior figures having sex in a house allegedly hired by the party for the purpose of extra-marital affairs.
Ten high-ranking officials have already quit over the scandal, and Birol Baskan, a Turkey specialist at the Georgetown University School of Foreign Service in Qatar, said the party's MPs were at risk of losing their jobs as well.
"The MHP is now destroyed - morale is low and the party leader [Devlet Bahceli] is demoralised. I don't think they can survive this," said Baskan.
A scenario in which the nationalists failed to cross the 10 per cent threshold would be to the advantage of the AKP, said Baskan, with the extra seats it could expect to gain pushing it towards a two-thirds super-majority of 367 seats - a result that would enable it to rewrite the constitution without the consent of other parties, or even resort to a referendum.
That has led to bitter accusations that Erdogan has set his sights on detroying the MHP as a parliamentary force, and allegations - strenuously denied by the ruling party - that forces connected to, or sympathetic to, the AKP were behind the leaking of the sex tapes.
"Clearly it's becoming a very dirty campaign, simply because if one of the parties can be eliminated, then the governing party will reap the benefits of the extra seats, and then they can have a much easier time passing the new constitution" said Carkoglu.
Yet even with a parliamentary super-majority, any AKP attempt to radically change the political system would likely polarise the country, said Diba Nigar Goksel, the editor-in-chief of Turkish Policy Quarterly.
Since coming to power in 2002, the AKP has endured periodic run-ins with Turkey's traditional establishment, which accuses it of seeking to dilute the secularist foundations laid down by Mustafa Kemal Ataturk in 1923.
The most striking example of those continuing tensions is the ongoing investigation into the so-called Ergenekon - or 'Sledgehammer' - plot, which has seen hundreds of army officers, retired soldiers and journalists jailed, pending trial over allegations that they conspired to overthrow Erdogan's government.
Several of those defendants are standing for election from their prison cells as figureheads of opposition to AKP dominance, including Cetin Dogan, a retired general alleged to have been the plot's conspirator-in-chief.
"The unity and peace of our country is facing a serious threat," Dogan said in an appeal to voters.
But Goksel said efforts to write a new constitution could also reveal fractures within the ruling party itself.
While the AKP's success in elections has been built on in its ability to draw pragmatic support from a range of factions and interest groups within Turkey, that coalition would be much harder to sustain on "ideological issues", she said.
"The reason the AKP is able to get so many votes is because it is can go to different provinces with different messages," Goksel told Al Jazeera.
"In order to get this much support, you have to have very diverse groups and very diverse thinking in your party. That's a strength in some ways, but it is also a liability, because it makes the party contradict itself."
One issue that has already exposed apparent divisions within the AKP is Erdogan's stated preference for a presidential system of government.
While a more personality-driven style of executive politics would suit the charismatic former mayor of Istanbul, other senior AKP figures, including the current president, Abdullah Gul, and Bulent Arinc, the deputy prime minister, have expressed reservations.
Opponents have been more forceful in their objections. Kemal Kilicdaroglu, the leader of the main opposition Republican People's Party (CHP) accused the AKP of "despotic ambitions", while Nursen Mazici, a political sciences professor at Istanbul’s Marmara University, wrote that under a presidential system "Turkey would become an authoritarian model, like Venezuela".
Carkoglu said constitutional questions and Erdogan's combative political style would likely throw up problems after the election because there was "no tradition of forming consensus" in Turkish politics.
The AKP, which was fined and warned in 2008 by the country's constitutional court over alleged anti-secularist activities, could still encounter opposition from Turkey's staunchly secularist judiciary, he added.
The issue of greater rights for Turkey's estimated 14-million Kurdish minority also looks set to pose a problem for Erdogan and his party, both in the run-up to next month's vote and afterwards.
Having once courted support in the southeast with its "Kurdish initiative", which liberalised rules banning the use of Kurdish language and promised greater cultural rights, the AKP appears largely to have given up its quest for votes in the region, amid Kurdish discontent and a renewed insurgency by the separatist fighters of the Kurdistan Workers' Party (PKK).
Earlier this month, Erdogan told a rally in the eastern city of Mus that there was no longer a "Kurdish question" in Turkey. A few days later, PKK fighters attacked an AKP campaign bus in the Black Sea region of Kastamonu - killing one policeman - shortly after Erdogan had addressed a rally.
The PKK's jailed leader, Abdullah Ocalan, then threatened the government with a "great war" unless it began talks on greater Kurdish autonomy within days of the election.
Meanwhile the funerals of PKK fighters killed by Turkish forces have triggered periodic riots and angry protests on the streets of Diyarbakir, the main city in the restive southeast.
"No matter how many votes the AKP gains, no matter how masterful the government turns, no matter if the prime minister becomes president, and no matter how remarkably Turkey grows, without finding a solution to the Kurdish conflict, nothing will work or become sustainable," wrote Cengiz Aktar in the Hurriyet newspaper.
Baskan said the Kurdish issue was the weak point of Erdogan's campaign for re-election, with independent candidates representing the Peace and Democracy Party (BDP) likely to gain votes at the AKP's expense in Kurdish-majority districts.
"Even among the Turkish population, there is a suspicion that Erdogan cannot manage this problem effectively," he said.
But he said the threat of Kurdish unrest, and speculation over Erdogan's presidential ambitions, were distractions from the main debate over what a new constitution for the country should look like.
"This is about much needed developments to turn Turkey into a much more liberal democracy; freedom of speech, freedom of religion, these constitutional reforms are top of the agenda, rather than the merits of a presidential versus a parliamentary system. What sort of secular system do we want? These are the real issues that this election is about."