Since coming to power in 2002, Erdogan has lifted the ban on women wearing head scarves, built 17,000 mosques, banned kissing in public and recently passed a law restricting the sale and advertising of alcohol.

Protestors say these are all signs of a creeping Islamization of Turkey.

"We are continuing this resistance. It started three to four days ago. People don't see what's happening to our country," one protestor warned.

Demonstrations have hit 48 cities across the country. Police are accused of being heavy-handed. Turkey is a key American ally in the region.

But U.S. Secretary of State John Kerry called Erdogan to show restraint.

"We are concerned by the reports of excessive use of force by police," Kerry said.

At the heart of this crisis experts say is a battle between secular, liberal-minded Turks and those who want to turn the country more conservative, more Islamic.