Ahmet Davutoğlu Thursday held a press conference at his party's headquarters in Ankara to announce his decision to step down as prime minister and chairman of the Justice and Development Party (AK Party). "I decided for the sake of party unity that a change of chairman would be more appropriate," he told reporters. "I am not considering running in the May 22 congress." Mr. Davutoğlu's decision ends a tradition of strong premiers in Turkish politics. Over the next months, the country will transition to a de facto presidential system.Before jumping to conclusions about the how, let's spend some time on the why.In 2001, the AK Party rose from the ashes of Necmettin Erbakan's Welfare Party (RP), which the Constitutional Court had banned as part of an ultra-secularist purge. The newly-formed political party, which represented a broad coalition of reformists, caught pundits and talking heads off guard by winning a landslide victory in the 2002 parliamentary election and becoming the first movement to secure a parliamentary majority since the late 1980s. Over the next 14 years, Recep Tayyip Erdoğan, the AK Party's founding leader, led his supporters to 10 consecutive victories including three municipal elections, two constitutional referendums and a presidential race.Succeeding a series of inadequate coalition governments, the AK Party restored political stability and implemented crucial reforms to fuel economic growth. Building on major accomplishments at home, Mr. Erdoğan's government became a G20 member and launched formal membership talks with the European Union. In addition to curbing the military's influence over civilian politics - which had led to three military coups since 1960 - the AK Party leadership significantly improved Turkey's human rights record and took unprecedented steps to promote minority rights and equal citizenship.During Mr. Erdoğan's tenure as prime minister, his party's problems with the bureaucratic establishment has been a recurring theme. In 2002, he was declared ineligible to run for public office in an effort to stop the AK Party in its tracks. Five years later, the Constitutional Court delivered a controversial verdict to prevent the election of then Foreign Minister Abdullah Gül, whom the establishment considered a threat against secularism, as Turkey's 11th president. With the Parliament in a deadlock, massive protests erupted across Turkey as the military issued a thinly-veiled threat to overthrow the country's democratically elected government. In the end, Mr. Erdoğan called for early elections and let the Turkish people settle the score. In a historic election that paved the way to the Gül presidency, Erdoğan's party won a stunning 46 percent of the vote.Months later, the AK Party government moved to amend the 1982 Constitution, under which the presidency was designed to empower the establishment at the expense of elected representatives. To prevent future confrontation between the government and the establishment, a constitutional referendum was held in 2007 to let the people, as opposed to the Parliament, elect the president - a proposal that 69 percent of voters supported. Seven years later, Mr. Erdoğan became Turkey's first elected president as then Foreign Minister Ahmet Davutoğlu replaced him as AK Party chairman and prime minister. The introduction of an elected president to the mix, however, created a problem of dual legitimacy - two leaders speaking on behalf of the people.In light of Prime Minister Ahmet Davutoğlu's decision to step down as prime minister and AK Party chairman, it is necessary to ask why two people who share the same ideology and come from the same background could not just work together.To be clear, the problem was institutional, not personal. Under the current rules of the game, it was impossible for Mr. Erdoğan and Mr. Davutoğlu to work together. Despite having been elected president two years ago, Mr. Erdoğan remains the undisputed leader of the AK Party. As a politician with vast influence over the Turkish people, he is a legitimate representative of the people, who have certain demands from the president. In recent days, Turkey's leaders took preemptive action to prevent a future crisis.Moving forward, the AK Party leadership must take necessary steps to address and alleviate systematic errors. At the convention on May 22, the party will take the first step toward realignment by electing a new chairman capable of working with the president to continue reforming the system. Under new management, the AK Party should take steps to reassure investors and promote economic stability. Meanwhile, President Erdoğan will remain the AK Party's de facto chairman.Prime Minister Ahmet Davutoğlu's decision to step down marks the beginning of an administrative reform process that will highlight the president's role as Turkey's chief executive and tasks the prime minister with coordinating the actions of cabinet members. In other words, Mr. Davutoğlu's decision means that Turkey has effectively adopted a presidential system.