SINCE ASSUMING the nominally ceremonial position of president in 2014, Turkish ruler Recep Tayyip Erdogan has aspired to endow it with far-reaching powers, replacing the country’s parliamentary system with something more like what Vladi­mir Putin has established in Russia. His autocratic ambition was fiercely opposed by liberal opposition parties, and last year the project seemed dead after Mr. Erdogan’s ruling party lost its majority. But Mr. Erdogan proved both resilient and ruthless: After launching a war against Turkey’s Kurdish minority, Mr. Erdogan called another election and won. Then, after a failed coup attempt in July, he orchestrated a far-reaching purge that has led to the arrest of about 40,000 people, including many who opposed his concentration of power.

Now Mr. Erdogan is moving forward with a restructuring that will convert Turkey from a Western-style democracy to something more like the Central Asian despotisms to its east. Under the reform introduced to parliament on Dec. 10, a new president will take office in 2019 with the power to name his own cabinet, introduce budgets and rule by decree. The parliament will be reduced to voting up or down on the executive’s edicts. Mr. Erdogan will find that familiar: He already has been ruling by decree under a state of emergency for the past five months. Having dominated Turkey since his Islamist party first won election in 2002, Mr. Erdogan, 62, would be permitted by the constitutional reform to remain in office until 2029.

Many Turks continue to resist the strongman’s entrenchment and will vote no in a referendum likely to be held early next year. But their leaders and media outlets are being systematically eliminated. The Committee to Protect Journalists reported on Dec. 13 that at least 81 journalists were imprisoned in Turkey during 2016 as a result of their work, more than in any other country. The leaders of the pro-Kurdish People’s Democratic Party, which campaigned against the presidential system, are under arrest along with 12 of the party’s parliament deputies. The referendum will be tilted in Mr. Erdogan’s favor.

The destruction of what, a decade ago, was frequently described as a model Muslim democracy could have momentous geopolitical implications. The European Union, which has been considering Turkey for membership, is pulling away in revulsion; only a deal under which Turkey is paid billions to prevent Syrian refugees from reaching Europe prevents a complete rupture. Though Turkey is a NATO member, Mr. Erdogan is drifting toward Mr. Putin’s Russia and talks of joining the Shanghai Cooperation Organization, a club led by Russia and China.

The Obama administration, which once looked to Mr. Erdogan as one of its closer allies, has appeared at a loss about whether or how to stop his power grab. The incoming Trump administration — or at least national security adviser-designate Michael T. Flynn — meanwhile appears intent on pandering to the strongman. Mr. Flynn has called for the extradition of Mr. Erdogan’s rival and alleged coup plotter Fethullah Gulen, even though the Justice Department has not completed an examination of Turkey’s case against him.

Secular and liberal Turks, who still compose nearly half of Turkey’s population, remain hopeful that the United States and European Union will somehow act to restrain Mr. Erdogan — or at least speak up clearly against his abuse of power. They are likely to be disappointed.