The former Soviet republic’s huge energy reserves and its strategic location along the Caspian Sea mean it is viewed by Europe as an important alternative to Russia for energy supplies.
Opposition parties say they are boycotting the presidential vote because of Aliyev’s sustained crackdown on dissent during his rule and a likely rigging of electoral results.
“We are not going to participate in this show,” Jamil Hasanly, head of the National Council of Democratic Forces, the Azeri opposition coalition, told Reuters.
The 56-year-old Aliyev and his supporters deny allegations of vote fraud or that dissent has been suppressed.
“Some political forces who decided to boycott the election have boycotted themselves as they were aware of their own defeat in advance,” Malakhat Ibragimova, a member of the ruling Yeni Azerbaijan Party, told Reuters.
Aliyev, first elected president in 2003, two months before his ailing father and long-serving leader Heydar died, cemented his position with two referendums - one in 2009 that scrapped a two-term presidential limit, and another in 2016 that extended the presidential term of office to seven years from five.
Aliyev brought forward the date of the latest vote to April 11 from Oct. 17, a move his allies said was necessary to avoid presidential and parliamentary elections clashing in 2025.
Seven other candidates were running in Wednesday’s election, which will have international monitors including the Organisation for Cooperation and Security in Europe (OSCE), but critics questioned whether the other candidates were genuine.
“Several OSCE ODIHR (Office for Democratic Institutions and Human Rights) interlocutors stated that the current legal framework and its implementation impede free election campaigning, noting previously voiced concerns over limitations to fundamental freedoms of expression, assembly and association,” the ODIHR said in a March 29 report.
Aliyev has tried to strike a balance between big regional power Russia, Azerbaijan’s former Soviet master, and the West, notably on energy policy.
His rule has benefited from an economic boom fueled by oil exports but a slump in global crude prices in the last three years has weakened the Azeri currency and shrunk the economy.
Many people in Azerbaijan are struggling on low incomes and amid a growing gap between rich and poor, and tensions are rising with neighboring Armenia over a territorial conflict that caused a war in the 1990s.
“I’m not going to vote as it’s very clear in advance that Ilham Aliyev will be elected as president,” said Gulshan Gajiyeva, a 20-year-old student.
There are 5.2 million eligible voters in the country of 9 million people. The president is directly elected by an absolute majority of votes cast, with no turnout requirement.
Polls open at 8 a.m. (0400 GMT) and close at 7 p.m. (1500 GMT). First official preliminary results are expected within hours of the polls closing.
Reporting by Naila Bagirova with additional reporting by Margarita Antidze for Reuters.