By Ercan Gurses and Orhan Coskun
ANKARA (Reuters) - President Tayyip Erdogan has made abundantly clear how he sees an April 16 referendum to change Turkey's constitution and create a stronger presidency - those who vote "no", he says, are siding with supporters of terrorism and a failed coup.
Erdogan, the most popular but also most divisive politician in modern Turkish history, has long cast himself as the champion of ordinary, pious Turks exploited by a secular elite. But some pollsters and people close to the ruling AK Party now think his polarising rhetoric risks scaring off moderate voters in April.
One AKP official put current support for the "yes" vote at 52-56 percent. A senior official told Reuters that in two of the party's own polls, the "yes" vote stood at 50-55 percent, highlighting the importance of undecided voters and the AKP's own liberal wing.
Erdogan and his supporters say Turkey needs a strong executive presidency, similar to the United States or France, to avoid the fragile coalition governments of the past that have hampered development. The president now has limited powers.
Opponents, including the main opposition Republican People's Party (CHP) and the Kurdish-rooted Democratic Peoples' Party (HDP), say the change would push Turkey toward one-man rule and the likely erosion of basic rights and freedoms.
Erdogan has seized on the HDP's opposition to buttress his case for change. He views the HDP as an arm of the outlawed Kurdistan Workers Party (PKK), which has waged a decades-long armed struggle against the Turkish state in the mainly Kurdish southeast. More than 40,000 people have died in the conflict.
"On one side there is a terror group which is trying to divide and dismember this country. There are those who act together with the separatist terror group," he said this week, referring to the PKK and the HDP respectively.
"Now what does the separatist terror group say? It says 'no'."
"The position of those who say 'no' is taking sides with July 15," Erdogan added, a reference to those who backed the abortive coup he has blamed on a U.S.-based Muslim cleric, Fethullah Gulen.
Turkey has become more deeply polarised since the coup, with authorities arresting tens of thousands of suspected Gulen supporters, including judges, journalists and soldiers, in a crackdown that has alarmed its NATO allies and rights groups.
In the referendum, Erdogan cannot take for granted the support of more liberal-minded AKP supporters. They represent a bloc of swing voters who in a June 2015 parliamentary election denied the AKP a parliamentary majority for the first time since it came to power in 2002. The party won 41 percent of the vote.
But as the security situation in southeast Turkey worsened, the AKP managed to win many back in a November 2015 snap election, securing 49 percent and a new parliamentary majority.
"The difference is the voting of our liberal supporters," said the first AKP official, comparing the two 2015 results. "If we can convince this segment to vote 'yes' in the referendum, we won't have a problem."
But the liberal segment may well blanch at Erdogan's terrorism rhetoric, which is designed to win over supporters of the nationalist MHP, parliament's fourth-largest party.
"The rhetoric that lumps the 'no' voters and terrorists together will not be welcomed by anyone other than the nationalists," said Faruk Acar of the Andy-Ar polling company.
The MHP leader backs Erdogan's executive presidency, but some others in the party are undecided or oppose the referendum, including Meral Aksener, who mounted a failed leadership challenge last year.
On Saturday when Aksener was addressing a rally at a hotel whose owners are seen as close to Erdogan, the electricity was cut in the building, the Cumhuriyet newspaper said, silencing the audio system and forcing her to continue using a megaphone.
"The power being cut during Meral Aksener's rally and cases where those voting 'no' are labelled terrorists cause discomfort among some AK Party members," said a source close to the party.
(Writing by Tuvan Gumrukcu and David Dolan; Editing by Gareth Jones)