After a historic vote, Vladimir Putin could remain in power in Russia until 2036. Here are 15 of the world's longest-serving leaders.

This week, Putin won a referendum on constitutional changes that would allow him to remain in power until 2036. The results of the vote were published five hours before the polls closed, causing critics to question its legitimacy, according to The Independent.

Nazarbayev was the first president of Kazakhstan. In 1991, under his leadership, Kazakhstan declared independence from the Soviet Union. Nazarbayev remained in power after a constitutional amendment made him exempt from a two-term limit on his presidency.

Kagame won Uganda's first multi-party election in 2003, though he reportedly used tactics like arresting supporters of his opponents and forcing other candidates to withdraw. According to the BBC, "His regime brutally suppressed the opposition and killed some of his most vocal critics — a charge his allies vehemently deny."

Daniel Ortega was a leader in the Sandinista Party who overthrew the Nicaraguan government in 1979, which led him to secure the presidency in 1984. He took office in 1985. According to the Washington Post, critics viewed the Sandinista as anti-democratic, but Ortega insisted otherwise. After he was voted out in 1990, Ortega lost three straight elections before becoming president again in 2007.

In 2016, Guelleh won a fourth term. The election was criticized by opponents for political repression, including police brutality and media bias, according to the BBC.

Malielegaoi, the leader of the Human Rights Protection Party, won re-elections in 2001, 2006, 2011, and 2016.

Lukashenko supported a partnership with Russia and worked closely with Russian President Boris Yeltsin. He pushed for a new constitution in 1996 that would give him greater powers, including a longer term and the right to rule by decree. According to The Guardian, he is "sometimes described as 'Europe's last dictator.'"

Rahmon was elected to his second term as president in 1997, and in 2003, a referendum was passed that allowed him to serve two more terms. According to Business Insider, he "has led the government in repressing political opposition and dissent."

Afwerki was elected to be both president and chairman by the National Assembly, which gave him power in both the executive and legislative branches of government. Afwerki would go on to serve as both chairman of the country's only political party and commander in chief of the army. According to Al Jazeera, "Rights groups report that journalists and dissenting politicians have been rounded up and imprisoned without trial."

In 1996, Déby was elected in the first multi-party election in the country's history. However, his 2001 re-election win was marred by allegations of voter fraud and irregularities, according to The New Humanitarian.

Eighty-year-old Ayatollah Khamenei became supreme leader after the death of the nation's first supreme leader, and founder of the Islamic Republic, Ayatollah Ruhollah Khomeini.

Khamenei has kept a firm grip on power. According to the BBC, his 2009 re-election led to one of the largest protests in the nation's history and saw protesters dealt with violently. He maintained that he won fairly.

Museveni took over after ousting the military regime of General Tito Okello, who had ruled for just six months. He consistently wins a substantial proportion of the popular vote in elections.

According to Voa News, Museveni was criticized for leading a march against corruption in 2019, and in 2018, Uganda was ranked as one of the most corrupt countries in East Africa by Transparency International.

According to the BBC, Sen lost re-election in 1993 but, refusing to accept the results, insisted upon becoming second prime minister alongside Prince Norodom Ranariddh. In 1997, Sen took over again after a violent coup in which Ranariddh was forced to leave Cambodia.

Nguesso won a landslide victory for his third term in 2016, though the opposition claimed it was due to fraud, according to the BBC. His win came after a referendum to remove term age limits, which would have prevented him from running again.

At 87 years old, Biya is the oldest leader in Africa. The BBC referred to Biya as Cameroon's "absentee president," for the extensive amount of time he spends abroad, particularly in a Swiss hotel in Geneva.

Mbasogo seized power from his uncle, President Francisco Macias Nguema, who was later tried and executed. Mbasogo has reportedly won landslide victories in his re-elections, though Humans Rights Watch has documented his administration's suppression of opposition groups, and overall corruption.

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