The opposition to President Recep Tayyip Erdoğan's rally in the German city of Cologne scheduled for next month grows as German politicians have expressed their dissent. The increasing opposition of German politicians toward the president's rally has drawn ire in Turkey, raising concerns about freedom of expression in Germany. Martin Schulz, the former president of the European Parliament (EP) and the German Social Democrats' candidate for the federal elections in September, said that he shares the concerns of Nordrhein-Westfalen (NRW) Interior Minister Ralf Jäger about Erdoğan's rally in Cologne next month. Jäger told the German newspaper Kölner Stadt-Anzeiger that the NRW has already suggested to the Federal Government the rally should be cancelled.Even though Schulz said Erdoğan is welcome in Germany, like any other leader of a friendly country, he called on the Turkish president to obey the country's laws.In addition, Turkish-German politician Green Party Co-Leader Cem Özdemir said the German government should make it clear to Erdoğan that he is not welcome in Germany.A similar incident took place in the country at a Turkish rally in Cologne following the July 15 coup attempt. Tens of thousands of Turks living in Germany gathered in the city to show solidarity with their compatriots back home, condemning the July 15 coup attempt perpetrated by the Gülenist Terror Group (FETÖ). Before the event, Germany's highest court decided to prevent President Erdoğan from addressing the rally. Earlier on Sept. 3, 2011, German authorities allowed senior PKK commander Murat Karayılan to address a crowd at a culture festival.Erdoğan is expected to visit several European cities prior to the referendum in Turkey, which will be held on April 16. The Turkish people will cast their votes to decide if the constitutional changes will be implemented. The Turkish president has been advocating an executive presidential system in Turkey for years.The registered 2.3 million Turkish voters living abroad will be able to cast their votes in 57 countries, and at Turkey's 119 foreign missions and 32 customs stations. With an estimated 3 million people, the largest Turkish community abroad is based in Germany.