Protests against plans to replace an Istanbul park with a shopping mall have spread across Turkey, metastasizing into something far more politically significant. While the demonstrations aren’t the start of a Turkish Spring, they show why Prime Minister Recep Tayyip Erdogan’s design to turn his country into a presidential republic next year should be stopped.

The police response to the Gezi Park protests has been brutal, injuring hundreds of people and turning central Istanbul into a battle zone. The nation’s leader should have tried to defuse the situation by listening to the protesters’ concerns and calling for restraint from the security forces. That is how President Abdullah Gul responded.

Erdogan instead dismissed the protesters as “looters,” “bums” and “extreme elements.” His government had won the last elections, he said, so it would continue with construction in Gezi Park. If not a shopping mall, then at least a copy of Ottoman-era military barracks would be built there, as well as a mosque on the adjoining Taksim Square.

Taksim is Turkey’s primary meeting place for public dissent and is at the center of a secularist playground of bars and nightclubs. Putting a mosque on the square is a politically aggressive move whose significance no Turk would miss.

Erdogan’s response has fed the fears of many secular Turks that he is bent on pursuing an authoritarian, Islamist and neo-Ottoman agenda. Emotions were already running high after parliament last week rushed through legislation banning all advertising of alcohol and its sale in stores after 10 p.m., among other restrictions. “Whoever drinks alcohol is an alcoholic,” Erdogan said on June 2 to justify the move.

Tens of thousands of Turks took to the streets over the weekend and more hung out of their windows to bang on pots and pans in protest. Police arrested about 1,700 people in 67 cities across Turkey, according to the interior minister.

This is a turning point to which governments in the U.S. and Europe should respond. Turkey has too few checks and balances on the prime minister’s power, and its democratic foundations -- including an independent judiciary, free media and strong political parties -- are shallow. This is why the country cannot afford Erdogan’s plans to have the constitution altered to give the president, a largely ceremonial figure, the authority to issue decrees with the force of law, to dissolve parliament, to call elections and to decide whether to send the military into action. Such a change would concentrate too much power in the hands of a single figure.

If he succeeds in changing the system, then Erdogan -- who under his party’s rules shouldn’t serve a fourth term as prime minister -- would run for president next year and, if successful, become Turkey’s version of Vladimir Putin. Erdogan has failed to adjust to the reality that he is no longer the religious conservative underdog, struggling against a too-powerful military to create a civilian democracy. He is now in full control of the country -- and the changes he proposes would weaken, rather than strengthen, Turkey’s democracy.

Secular Turks and the country’s woefully inept opposition parties should focus their energies on preventing the constitutional change that Erdogan wants. They might even find allies within the prime minister’s own party, and possibly win the support of President Gul, as well.

The U.S. and the European Union can help by making the argument against Turkey becoming a presidential republic, and by relentlessly highlighting the jailing of journalists and other abuses of free speech, judicial independence and civil liberties.

Erdogan is the most important leader Turkey has had since Mustafa Kemal Ataturk founded the republic in 1923. Erdogan has brought enormous change for the better, including an economy that has tripled in size since he came to office in 2003, and has reason to boast, as he did recently in Washington, that “the world is talking about Turkey.” There is, however, a good reason for subjecting politicians to term limits: After too long in office, they lose touch with the people they represent and become captives of their own propaganda. Erdogan is no exception.

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