President Recep Tayyip Erdogan outlined his vision at a stadium ceremony in the Aegean port of Canakkale, near where Ottoman armies held off an Allied expeditionary force in 1915-1916, a bloody event that helps to underpin staunch nationalism in Turkey today.
While Turkey calls it the Canakkale battle, its former Allied adversaries, including Australia and New Zealand, refer to it as the Gallipoli campaign.
Opponents of the democratically elected president view the April 16 referendum as part of a dangerous drift toward authoritarian rule, though supporters see him as a pillar of stability, Muslim piety and nationalist pride in a turbulent region that includes neighboring Syria.
"We are offering historic reform," said Erdogan, who maintains that an executive presidency and the abolition of the prime minister's post will help Turkey develop economically and deal with security challenges, which included a botched coup attempt last year.
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Erdogan had harsh words for Europe, where some countries, citing security concerns, have prevented Turkish Cabinet ministers from campaigning for referendum votes in the Turkish diaspora.
"We have around 3 million voters living abroad," Erdogan said. European governments "hindered them," he said. "Let them try and hinder them. Whether Germans, Dutch, Austrians, Swiss, Belgians, Danes or whoever it is, know that your president has stood firm and will keep on standing firm."
Dutch authorities had refused to let Turkish ministers address Turkish citizens in rallies, prompting Erdogan to refer to "Nazi remnants" in the Netherlands. European Union leaders called the remark unacceptable.