Turks in Germany have streamed into Berlin's Olympic stadium, seizing the chance to vote from abroad for the first time in an election Prime Minister Recep Tayyip Erdogan hopes will make him Turkey's first directly-elected president.
Turkey itself goes to the polls on August 10 to choose between Erdogan and two opposition candidates. But expatriates, in the past allowed to vote only within Turkey's borders, are casting their ballots over the next four days.
For some Turks who came to Germany decades ago, it will be the first time they will be casting their ballots anywhere, said Safter Cinar of the group Turkish Community in Germany.
Ballots will be cast in Berlin and six other large venues nationwide until Sunday and then flown to Turkey, as will the results from more than 50 other countries, the AFP news agency reported.
Erdogan, who has dominated Turkish politics for more than a decade but is barred by party rules from standing for a fourth term as prime minister, has said the direct nature of the vote will imbue the presidency with far greater clout.
Polls suggest he will win the simple majority needed in the first round. Two surveys last month put him on 55-56 percent, a 20-point lead over his nearest rival, Ekmeleddin Ihsanoglu.
The diaspora vote will count as never before.
About 2.8 million Turks abroad are eligible to vote, around 1.4 million of them in Germany, a number equivalent to the electorate of Turkey's fifth largest city, Adana.
One million voters are based elsewhere in Europe, with smaller numbers in the US, Asia, Africa and Oceania, the Reuters news agency reported.
"It is hugely important for me to be able to vote in this election, and I want to see Erdogan, who has done so much for our country, continue," said Necrettin Koc, 40, who moved to Germany as a child and works as a builder in Berlin.
"I live in Germany, but I'm a Turkish citizen and care deeply about what happens there. I'm convinced that Erdogan will win in the first round," he said, speaking outside the imposing Berlin stadium built for the 1936 Olympics.
Turks comprise Germany's biggest minority as a result of decades of labour migration that began in 1961, which saw many young workers coming from some of Turkey's poorest and most remote areas - conservative heartlands where Erdogan draws his strongest support.
Today the German diaspora reflects Turkey's diverse political landscape, with conservative Muslim groups, left-wing trade unionists, Kurds and secularists all represented.
Erdogan visited the western German city of Cologne in May, courting the diaspora vote at a rally of 16,000 supporters, although an estimated 45,000 protested against him.
The pro-Kurdish party candidate Selahattin Demirtas also visited Cologne this month, and said he felt strong support.
"Turks are interested in politics here but also in Turkey, because they see their future in both countries," said Ahmet Basar Sen, Turkish Consul General for Berlin.
Erdogan enjoys huge popularity among a pious, conservative swathe of the Turkish population.
But he has alienated others with what critics see as inflammatory language and authoritarian instincts, exemplified by a heavy crackdown on anti-government protests last year and subsequent bans on Twitter and Facebook.
If Erdogan becomes president and the ruling AK Party wins 2015 legislative elections, he has said he wants to change Turkey's constitution to potentially enshrine the now largely ceremonial presidency with more powers.