By Ralph Boulton and Andrea Shalal
ISTANBUL/BERLIN (Reuters) - Tayyip Erdogan's portrayal of a Germany mired in its Nazi past was calculated to infuriate Berlin while swaying Turks at home and abroad to vote "yes" to sweeping new presidential powers he seeks.
Erdogan certainly achieved the first aim, with one German politician dubbing him the "despot on the Bosphorus" and Chancellor Angela Merkel declaring that the remarks only trivialised Nazi crimes against humanity.
“With his foolish and absurd Nazi comparison, Erdogan has left the realm of rational discussion," Juergen Hardt, a lawmaker from Merkel's conservative CDU party, said of Erdogan.
"While Germany sticks to democratic standards...President Erdogan is trying to disempower the Turkish parliament through a constitutional change."
Erdogan's fury was triggered by decisions to cancel planned rallies in support of his referendum in several German towns.
Events have so far been cancelled in the cities of Gaggenau, Cologne and Frechen, with local authorities or venue operators citing concerns about safety or the size of the crowd. Turkish officials said a fourth event in the town of Kelsterbach was cancelled on Monday.
Merkel has said her federal government played no part in the decisions. Government spokesman Steffen Seibert said Germany would allow Turkish politicians to speak, as long as they were open about their intentions, announced them in a timely manner and did not import Turkish conflicts to Germany.
The faithful at Erdogan's Istanbul rally registered their support for Erdogan's blustering speech with familiar chants of "Stand up straight! Don't bow down! The nation is with you!"
But his portrayal of "fascist" German officials banning rallies to discourage a "yes" vote may alienate some of the 1.5 million Turkish voters in Germany whose support he badly needs.
He could scarcely have used a more poisonous arrow against his NATO partner.
Gokay Sofuoglu, chairman of the Turkish community in Germany, told Reuters Erdogan’s rhetoric was increasing tension in an already divided Turkish community.
"Erdogan went a step too far," he said. "Germany should not sink to this level."
Sofuoglu appealed to members of Germany's Turkish community to stay calm despite what he called a constant barrage of anti-German and anti-European messages on Turkish media.
THE EMIGRE VOTE
A leader with no rival who consistently wins close to 50 percent in elections, Erdogan is well placed to win powers he says are essential to secure a country threatened by Islamist and Kurdish militants and still recovering from a military attempt to topple him that killed 248 people.
Opponents say the new system, allowing him to enforce decrees, dissolve parliament and declare emergency rule, would abolish checks already eroded during his 15 years in power.
The almost 4 million Turkish voters living in the European Union are an important bloc that could be sceptical of Erdogan's desire for more authority, said Abdulkadir Selvi, a commentator with close links to the ruling AK Party.
"Is the AK Party front uneasy about a 'no' wave across Europe and particularly in Germany? They are definitely uneasy, because votes overseas have begun to create a significant weight on the election results."
Germany is not alone in worrying about Turkish rallies. The Dutch government has opposed a rally in Rotterdam, while the Austrian chancellor proposed an EU-wide ban on Turkish rallies, which would deflect some of the pressure from Berlin.
"We now see a wave of fascism is being resurrected through Germany and Austria," Turkish pro-government newspaper Yeni Safak said in an editorial. "A racist trend is spreading across the whole of Europe preparing for open war against the two 'enemies', the Turkey enemy and the Islamic enemy."
There was room for humour amid the bluster, albeit with a sarcastic edge: "Don't be scared, we are not planning to besiege Vienna again," the editorial said, referring to 16th and 17th century battles that halted Ottoman expansion in Europe.
Erdogan has chafed at German criticism of a widespread purge he is conducting including arrests and dismissals of people in almost all walks of society suspected of links to the failed July coup. He has also accused Berlin of giving succour to Turkey's enemies, from Kurdish militants to leftist radicals.
Dozens of Turkish diplomats and military figures accused by Erdogan of links to the coup have claimed political asylum in Germany. The German justice ministry says it has received 136 asylum applications.
Erdogan has also bristled at German condemnation of the arrest of a German-Turkish journalist, whom he calls a spy.
Merkel's response is constrained in part by her reliance on Erdogan's cooperation in a deal that stopped the flow of migrants into Europe from Turkey last year, after a million reached Germany the year before. Erdogan agreed to take back migrants who reach the EU from Turkey by boat. In return, the EU agreed to easier visas for Turks and progress on Turkey's long-delayed bid to join the bloc.
The lead article in German news magazine Der Spiegel urged Merkel to free herself from the “handcuffs of the migrant deal”.
Erdogan has made no hint so far that he might pull out of the deal, but Turkish officials grumble that Europe is not living up to its side of it.
“While we're expecting full support from Germany on issues such as the migrant deal, visa liberalization and Turkey’s full EU membership, the exact opposite is happening," a senior government official said.
"There is a great disappointment in that sense.”
(additional reporting by Tuvan Gumrucku, Orhan Coskun, Daren Butler, Tulay Karadeniz; editing by Peter Graff)