Erdogan is expected to run for Turkey's presidency in August, and Germany -- with a Turkish community of three million, half of them eligible voters -- would be a strong constituency for the controversial leader.
The premier urged the adoring crowd to register for the election, the first in which overseas Turks don't have to travel to the homeland to vote, and added: "God willing, we will announce our presidential candidate as soon as possible."
In the western German city of Cologne, where Erdogan spoke, at least 40,000 protesters marched on the opposite bank of the Rhine River from the venue, waving banners that read: "Resistance against AKP fascism" and "Corruption, sharia, sultanate -- Erdogan, you are not a democrat".
However, inside the arena, Erdogan was cheered by a flag-waving and emotional crowd of some 20,000 as he forcefully stoked their Turkish pride and attacked his political enemies at home and abroad, including in the German press.
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Cheered on loudly by his conservative followers, many waving the red-and-white Turkish flag, Erdogan accused street protesters in Turkey of "terrorist acts" and highlighted sweeping wins for his AKP party in March 30 local elections.
"If we believe in democracy and the ballot box, if we respect election results, then we have to respect the decision of the Turkish people," he said.
Accusing his critics of "arrogance", Erdogan -- hailed by his followers for driving rapid economic growth, raising Turkey's world status and building many megaprojects -- intoned that "today's Turkey is not that old Turkey!"
Many demonstrators wore hardhats with the word "Soma" on them, the western Turkish town that was the site of Turkey's worst ever industrial disaster.