Turkey's presidential front-runner promised to uphold secular principles despite the doubts of skeptics, ahead of the start of voting Friday that highlights tensions between the defenders of secularism and the Islamic-rooted government. "I am loyal to the republic, to secularism, to the principles of a democratic, social state ruled by law, as stated in the Constitution in essence," Foreign Minister Abdullah Gul said in an interview published Thursday in the Milliyet newspaper. The comment echoed a recent statement by military chief Gen. Yasar Buyukanit, a guardian of the secular principles enshrined in the Constitution. He had said the president must be loyal to secularism "not just in words, but in essence." As the ruling party candidate, Gul is almost certain to win the presidency in a series of parliamentary votes that begin Friday.