The European Parliament has called on European Union leaders to open entry talks with Turkey "without undue delay" when they meet in Brussels this week.
EU attitudes to Turkey's possible membership differ widely
A non-binding resolution supporting the start of accession negotiations was backed by 407 MEPs, with 262 against.
Dutch Prime Minister Jan Peter Balkenende, who will host the summit, says he wants a unanimous decision from the leaders of the 25 member states.
Turkey has said it is not prepared to join the EU "at any price".
Earlier on Wednesday, Turkish Foreign Minister Abdullah Gul told the Turkish Milliyet daily that there were four "red lines" that Turkey would not cross:
- Negotiations must have Turkey's complete membership as the final aim
- Turkey must not be forced to extend diplomatic recognition to the Republic of Cyprus
- The decision to start talks must not be conditional on subsequent decisions by EU leaders
- There should be no special conditions imposed permanently on Turkey
Mr Balkenende, whose country holds the EU's rotating presidency, has said he expects leaders to vote in favour of opening talks.
"On the basis of the contacts that I've had, a 'yes' seems likely to come, but we need a unanimous decision," he told the Dutch parliament on Wednesday.
The resolution also called for close monitoring of Turkey's progress in improving human rights, religious freedom and women's rights. It said talks should be suspended at any time if Ankara wavers in these areas.
Amendments suggesting Turkey should be offered a special partnership instead of full membership, or that it should be rejected altogether, were defeated.
Before the vote in Strasbourg, European Commission President Jose Manuel Barroso told MEPs it was "time for the European Council to honour its commitment to Turkey".
"A clear date should be indicated," he said.
"We accept that the accession process is open-ended and its outcome cannot be guaranteed beforehand."
Earlier, he told French television: "This doesn't yet mean membership for Turkey, it will take time naturally, but I think we will now be able to start the process of
negotiations with Turkey which has made huge efforts to come and join the European Union."
The BBC's Chris Morris says the number of votes against the motion reflects considerable misgivings in parts of Europe about starting membership talks with such a large, poor and overwhelmingly Muslim country.