AFP, ISTANBUL: Turkish voters went to the polls Sunday in a bitterly-contested election set to determine whether President Recep Tayyip Erdogan can tighten his increasingly controversial grip on the country. The legislative election is taking place under the shadow of violence, after two people were killed and dozens more wounded in an attack on a rally of the pro-Kurdish People's Democratic Party (HDP) in the southeastern city of Diyarbakir on Friday. Opinion polls predict that the ruling Islamic-rooted Justice and Development Party (AKP), co-founded by Erdogan and in power since 2002, will again win the most votes, but its share could be sharply down on the almost 50 percent it gained in 2011 elections. Erdogan wants the AKP to win a two-thirds majority of seats, which would allow parliament to push through a new constitution to switch Turkey from a parliamentary to a presidential system. This would enshrine the position of Erdogan -- premier from 2003-2014 before becoming president -- as Turkey's number one and transform the office of the presidency which was largely ceremonial until his arrival.