Turkey is voting in a general election which will determine whether President Recep Tayyip Erdogan’s ruling party, AKP, can change the constitution.

President Recep Tayyip Erdogan, who first came to power as prime minister in 2003, is seeking a big enough majority to turn Turkey into a presidential republic.

However, the pro-Kurdish HDP may cross the 10% threshold and enter parliament.

Explosions at its election rally in Diyarbakir on June 5 killed four.

Photo AP

Officials said the blasts were caused by improvised bombs.

HDP leader Selahattin Demirtas criticized Recep Tayyip Erdogan’s response to the killings.

If the left-wing HDP succeeds in winning seats in parliament for the first time, it would reduce the number of seats won by Recep Tayyip Erdogan’s AKP, thwarting its plans to change the constitution and transfer the prime minister’s executive powers to the president.

Recep Tayyip Erdogan served as prime minister until he won the presidential election in 2014.

A strong showing by the HDP might well deprive the ruling AKP of a parliamentary majority.

Sunday’s election is the biggest electoral challenge for the AKP since it came to power 13 years ago.

The result may also have ramifications beyond Turkey’s borders.

Turkey is a vital NATO member in a volatile Middle East and a rare mix of Islam and democracy.