On April 20, Iran’s Guardian Council announced the slate of six candidates who will compete in the May 19 presidential elections. In recent months, as the vote has approached, the conventional wisdom among political observers has been that the election is incumbent President Hassan Rouhani’s to lose. But a series of surprises have cast doubt on this expert consensus: Former President Mahmoud Ahmadinejad put in a surprise bid for candidacy on April 12, against the stated wishes of Supreme Leader Ayatollah Ali Khamenei, while recent polls of voter preferences for prospective candidates show a tighter race than anticipated. This increased competition is a crucial component of elections in Iran.

Historical trends suggest that Rouhani will be the likely winner next month. But it is in the interest of the political establishment to aim for a competitive election while keeping the scales in Rouhani’s favor. Managed uncertainty helps drive voter turnout, and high levels of electoral participation are valuable for the Islamic Republic. In a country with a diverse, politically active and young population, the democratic process is an important tool that is used to channel political engagement. It is in the supreme leader’s interest to ensure that the democratic process is perceived as legitimate and serves as a tool for mass participation in the political process.

This has been particularly clear under Khamenei’s leadership. The first presidential election after the 1989 death of his predecessor, Ayatollah Ruhollah Khomeini, saw President Akbar Hashemi Rafsanjani easily re-elected with historically low voter turnout; only 50.66% of eligible voters came out to the polls in 1993. That set an alarm that ramped up campaigning efforts, leading to a much more competitive election in 1997, which brought participation up to nearly 80%. Since then, election campaigns have attracted between 60-70% of voter turnout with an all-time historic high of 85% during the disputed 2009 elections, which led to escalated division and conflict.

Despite this managed uncertainty, election outcomes have been consistent to such an extent that it is essentially an unwritten rule of Iranian politics that, short of a political catastrophe, Iranian presidents serve a second term — but never a third. This allows a necessary level of continuity in foreign and domestic policies that allows the incumbent administration to capitalize on diplomatic ties built during its first term. Indeed, the two-term presidency gives the executive enough time to be effective without allowing him to entrench himself in the government so deeply that he could challenge the political order or the role of the supreme leader.