The European Commission says talks on Turkey's membership of the EU should start on time on 3 October with accession as a "shared objective".
Gateway to Asia: A new dawn or twilight for Turkey's EU ambitions?
The recommendation is made in a proposed framework for the talks, which member states must approve unanimously.
The commission says the talks should be open-ended, and that Turkey will not be able to join until 2014 at the soonest.
Its proposal comes as enthusiasm for enlargement wanes in the wake of French and Dutch votes on the constitution.
Voters in both countries said they were concerned about the impact of EU enlargement on jobs, and some raised particular concerns about Turkey, a Muslim country whose population is on course to be bigger than Germany's by 2015.
EU Enlargement Commissioner Olli Rehn said the 25-member commission took its decision on the mandate after "a lengthy, argumentative and very political debate".
He said some speakers raised the idea of agreeing a "special relationship" with Turkey rather than full membership.
The BBC's Chris Morris in Brussels says like other would-be members in the future, Turkey will also face much stricter conditions than candidates in the past.
It is not just about human rights and democracy, he says, but also a host of technical issues which will take years to resolve, including agricultural reform and environmental standards.
But the biggest hurdle will be a political one, our correspondent adds.
Although the current French and German leaders are in favour of Turkish membership, their successors may not be, he says.
Before the membership talks can begin, Turkey must sign a protocol extending its customs union to the 10 new EU members, including Cyprus, a country it does not officially recognise.
"The negotiations will be based on Turkey's own merits and the pace will depend on Turkey's progress in meeting the requirements for membership," the negotiating mandate says.
Mr Rehn said that if Turkey must at least be assured of a special relationship with the European Union even if it does not ultimately gain membership.
"If Turkey is not in a position to assume in full all the obligations of membership it must be ensured that Turkey is fully anchored in the European structures through the strongest possible bond," he said.
Despite the cooling of attitudes towards enlargement since the French and Dutch referendums, a Eurobarometer study published this week suggested that the issue had not been a major factor behind voters' rejection of the constitution.
The poll said only 6% of Dutch voters and 3% of French voters gave enlargement as the reason for their "No" vote.
Opposition to Turkish membership, in particular, was cited by 3% of Dutch "No" voters and 6% of French "No" voters as the reason for their choice.