Now, weeks before membership talks are to finally begin, there are increasing fears in Ankara that the Europeans are not serious about a commitment.
The latest cause for concern comes from Germany, where a victory for the front-running conservative candidate Angela Merkel could bring to the fore a powerful new opponent of Turkish membership.
If Merkel defeats Chancellor Gerhard Schroeder in the 16 September election as expected, the two engines of European integration - France and Germany - will be in the hands of leaders who have serious qualms about letting in the Turks.
Merkel has repeatedly said she does not support full EU membership for Turkey; French President Jacques Chirac has recently criticised Turkey over its refusal to recognise Cyprus.
When Merkel proposed a "privileged partnership" for Turkey instead of membership, Turkish Foreign Minister Abdullah Gul shot back that the idea was "illegitimate and immoral".
"I regret to see that a long-term issue as crucial as Turkey's future integration with Europe is being exploited for short-term domestic political calculations by some circles," Gul said in an interview with the Turkish Daily News.
Turkey wants a Turkish-Cypriot state
Erdogan said Merkel's notion of a partnership "is like sitting at the wedding table and saying, 'Let's be friends'." But despite the tough talk, neither the EU nor Turkey seems interested in a serious rupture.
"Nobody has anything to gain from that," said Ilter Turan, a political scientist at Istanbul Bilgi University.
Keeping a secular, Muslim state like Turkey close to the West is a crucial US and Western goal that became more important after the September 11 attacks.
Any firm rejection of Turkey by Europe could strengthen Islamists and nationalists in Turkey, which could draw the country away from the West.
With fighting in neighbouring Iraq and tensions between another neighbour, Iran, and the United States increasing, Turkish stability has become critical for the West.
In the United States, officials are keen to showcase Turkey as an example of a Muslim country that has successfully pursued integration with the West.
"You are making a major foreign policy mistake," Schroeder told Merkel during their Sunday debate. "You do not understand what geostrategic, what geopolitical significance linking Turkey to the EU has."
Some Turkish generals say they are
constrained in fighting separatists
EU officials have stressed that they expect talks with Turkey to open on 3 October, as scheduled, but many in Turkey fear that the talks will move slowly due to European opposition.
"It is easy to predict there will be problems," said Bulent Aliriza, an analyst with the Washington-based Centre for Strategic and International Studies.
And there are fears that Turkish leaders could lose their will to press forward with the sweeping democratic reforms that they started in an effort to boost the EU bid if the talks stall.
Some Turkish generals are complaining that they are being constrained in their fight against Kurdish separatists.
"It is not a given that the reform process will continue," Aliriza said. "It is very much a result of the EU process."
The government, however, has stressed that it is committed to reforming and is emphasising that EU talks could take a decade.
"There is no doubt that both Turkey and Europe will be different then from today," Gul told The Turkish Daily News.
Italian Foreign Minister Gianfranco Fini said on Tuesday that Turkey was ready to start EU-entry talks next month and should not be asked to recognise Cyprus until after those negotiations begin.
"You do not understand what geostrategic, what geopolitical significance linking Turkey to the EU has."
"It would be a mistake to pose any additional conditions on Turkey," Fini said after meeting Greek Foreign Minister Petros Moliviatis.
"Turkey has already fulfilled all the requirements necessary for negotiations to begin."
Turkey's talks towards eventual EU membership are to start on 3 October, but officials in France have said Ankara should clarify its position on Cyprus first.
Cyprus has been divided since 1974, when Turkey invaded the island after a short-lived coup backed by the supporters of union with Greece.
Ankara supports a Turkish-Cypriot breakaway state in the north of the island and not the internationally recognised Greek-Cypriot government in the south.