Sunday's referendum is aimed at abolishing the office of the prime minister and giving more executive powers, including issuing decrees, declaring emergency rule, appointing ministers and state officials and dissolving the parliament, to the now largely ceremonial position of president in Turkey.
The referendum will take place under a state of emergency that has been in place since last summer's failed coup, which has seen some 47,000 arrested in the biggest crackdown in Turkey's history. Critics worry a "yes" vote on Sunday would further empower a leader they say has dictatorial tendencies, while Erdoğan's supporters say the constitutional changes would give their leader the authority he needs to strengthen the economy and fight terrorism.
Former interior minister Meral Aksener, a two-decade veteran of politics, was seen as the most credible internal challenger to Bahceli until she was expelled from the MHP past year. Due to ongoing clashes between outlawed Kurdistan Workers' Party (PKK) and Turkish forces, the government is paying special attention to poll safety.
The president would be able to remain a member of a political party or even lead it - ending the tradition of presidential impartiality. Turkey today is increasingly isolated, particularly from the West. Last month, he lashed out at Germany for using "Nazi tactics" and called the Dutch "fascists" and "Nazi remnants" for blocking efforts to campaign for the referendum in the Netherlands. Erdogan's supporters reject such charges, saying the 18 constitutional amendments being put to a simple "Yes/No" vote contain sufficient checks and balances, such as the provision that a new presidential election would be triggered should the president dissolve parliament.
Hawaii issues alert for brain-invading parasite transmitted by snails
The confirmed cases on Maui involve four residents and two visitors, and the confirmed cases on Hawaii involve residents only. Based on the data provided by the Atlantic the first documented case of this infection appeared in Taiwan back in 1944.
Polls suggest a neck-and-neck race for Sunday's vote.
After a ceasefire broke down in July 2015, Erdogan vowed to crush the militants, boosting his popularity with nationalist voters at Bahceli's expense. In the face of a defeat at the ballot box, he is likely to amp up his war against the Kurds, making him seem like an embattled defender of the nation. "April 16 will be an answer to the European Union", Erdogan said in a TV interview late on Thursday.
The "yes" campaign - backed by Erdogan, Prime Minister Binali Yildirim and the ruling Justice and Development Party - has dominated Turkey, while the opposition "no" camp have faced threats, violence, arbitrary detentions, a lack of TV airtime, and disregard by pro-government media.
But it has become an unlikely ally in Erdogan's quest for a presidential system to enhance his powers.