France and Luxembourg congratulated Romano Prodi after he claimed victory in the Italian elections.
They are hoping his experience as European Commission president meant Rome would take a more active part in Europe.
His successor in Brussels, Jose Manuel Barroso, also hailed a victory for Mr Prodi as good for Europe but said any official European Commission reaction had to await the final result.
Outgoing Prime Minister Silvio Berlusconi steered Italy on an unusually distant course from the European mainstream and made few friends among fellow leaders of EU member states.
European Affairs Minister Catherine Colonna of France, which has felt isolated in Brussels in recent years, sent a friendly letter congratulating Mr Prodi and looking forward to co-operating with him in relaunching efforts at European integration.
In Strasbourg, where he was attending a meeting of European Union and Council of Europe officials, Mr Barroso told a news briefing: "We will work very well with the new Italian government. It will be, in the great Italian tradition, a government that is enthusiastic for Europe."
He said the commission would wait until the final result before issuing an official statement.
Luxembourg Prime Minister Jean-Claude Juncker, who was also attending the meeting in Strasbourg, told Reuters a Prodi victory heralded a strongly pro-European stand in Rome.
"I hope - in fact I'm convinced - that Italy's policies will be very openly pro-European, notably because of the personality of Mr Prodi," he said.