The EU wants Turkey to change its definition of terrorism in return of visa-free travel, but Turkey refuses to entertain the EU's request.
A deal which could see Turkish nationals travelling thought Europe without visas is on the edge of collapsing.
This comes after the European Union (EU) requested Turkey to change its law on terrorism, one of 72 conditions set out in the deal.
The EU Commission President Jean-Claude Juncker on Wednesday said the deal would collapse unless Ankara doesn't change its anti-terror laws.
"We put great value in the conditions being met. Otherwise this deal, the agreement between the EU and Turkey, won't happen."
Turkish officials are openly rejecting this condition, saying that it would result in changing its stance against terror.
In response, Turkish President Recep Tayyip Erdogan on Thursday slammed the EU for even making such a condition.
He says it would harm the efforts put out against terrorism.
"Asking Turkey to revise its terror law means to give up on the cause. If the EU wants to address the terrorist group [PKK] instead of the Republic of Turkey, we are ok with it."
He added that Turkey looks at those who defend causes of terrorist groups the same way it looks at terrorist groups.
The deal, which is aimed at decreasing the illegal influx of refugees into Europe was reached between Turkey and the EU in March.
The main aim is to let Turkey control the influx of refugees into Europe.
In return for meeting all 72 conditions, the EU will provide Turkey with financial aid, visa-free travel and progress its EU membership negotiations.
All but one condition has been met by Turkey, thus far.
The EU Parliament caused tension between both sides when it debated on Turkey's anti-terror laws on Wednesday.
Some officials from EU member countries are trying to ease the tensions and prevent a possible collapse.
Germany's Foreign Minister Frank-Walter Stenmeier warned other members on Thursday that the EU has "a strong interest to ensure the agreement on migration should not collapse."
"We cannot ignore the fact that Turkey is a key country for stopping irregular refugee flow towards Europe, and therefore we need such agreements."
The deal now remains on edge until both sides reach a compromise.