EU leaders meet on Thursday to discuss a possible deal with Turkey to limit migration to Europe in return for concessions for Ankara.
Turkish Prime Minister Ahmet Davutoglu is expected to join EU leaders on Friday.
The following are comments by EU heads of state and government and senior EU officials before the meeting.
Greek Prime Minister Alexis Tsipras
"We are here today in order to try to reduce or to stop the illegal flows from Turkey to the Greek islands but at the same time to create a robust for the refugees from Turkey to the EU and that means to accelerate the relocation and create a credible mechanism for resettlement from Turkey to the EU and I hope that the decision that we will take will be in the framework of the the international legislation, the Geneva agreement and the European acquis. Last but not least, I'm waiting today (for) a decision to assist Greece in these difficult circumstances especially in our northern borders in Idomeni. But we have to face a humanitarian crisis is due to unilateral actions. I think that this is a shame for a common culture and we have to take a decision to de-escalate the situation there and we have to find a way, through first aid, hospitality ... but at the same time accelerated relocation."
British Prime Minister David Cameron
"What matters today is actually busting the business model of these people smugglers and so therefore breaking the link between getting in a boat and getting settlement in Europe. So we support the idea of turning back people from the Greek islands back to Turkey, that is a good idea. But we ought to be clear here about Britain's special status in this organisation. Because we have kept our own border controls, because we are out of Schengen, we won't be offering visa-free access to Turks as part of this agreement. We maintain our own immigration policy. Also, we have already said what we are going to do in terms of taking Syrian refugees to Britain and that is underway and we won't be taking more because of what is discussed here today. But if we could get an agreement that returned migrants from the Greek islands to Turkey that would be good progress."
Belgian Prime Minister Charles Michel
"Better no deal than a bad deal."
"Turkey is asking for a lot. I won't accept what at times seems like blackmail."
Cyprus President Nicos Anastasiades
"If Turkey fulfills its obligations according to the Ankara negotiating framework there is no problem, but without it we can do nothing."
"I'm sure our partners will find a way. I hope that by tomorrow there will be an agreement."
Italian Prime Minister Matteo Renzi
"Europe cannot afford not to have a deal with Turkey, but must be a deal that respects our fundamental values"
Lithuania President Dalia Grybauskaite
"Pre-conditions have been agreed already... we are negotiating around the same conditions. I understand and support part of the criticism because I think the proposed package is very complicated, will be very difficult to implement and it is on the edge of international law."
Dutch Prime Minister Mark Rutte
(Netherlands holds six-month rotating presidency of EU)
"It's not a done deal. We have to do a lot today with the 28 (member states) and tomorrow with Turkey."
"What we want to achieve is for the crossings to stop. By being able to return people we expect them to stop within three to four weeks. After the Western Balkans were closed, which was important, the flow of people via Turkey to Greece will also stop and that is very important."
"We will have to make sure that everything is well-founded in legal terms. I notice from more and more colleagues that they have the impression that we have it all in order."
"Visa liberalisation can happen if all conditions are met. The EU has to make sure that we don't delay. That's an agreement we have made, even years ago in the Dutch parliament, we are prepared to give visa liberalisation to Turkey once they meet all the requirements. What they want is to speed things up, that's fine, but you will then have to also speed up. You have to show that you meet all 72 criteria."
"If we don't reach a deal the flow will continue, then people will continue to drown in the Aegean and Greece will fill up with migrants because the borders are closed. It's good those borders are closed and that the waving through of migrants has stopped in the Western Balkans. It is very important we get a deal."
"I tend to shy away from apocalyptic quotes. But I don't see how, if we don't get a deal today or tomorrow, we will get a deal at a later stage."
"There is no alternative. We have to come to a deal. Otherwise the situation in Greece will stay very difficult, the humanitarian crisis will increase as the Western Balkan route has been closed off and people cannot leave Greece. It is crucial we come to a deal today and tomorrow."