But insiders say he may break away from that alliance and is courting a centrist partnership with Mr Macron’s En Marche movement after Italy’s elections next month.
An Italian Socialist MEP told Politico: “There’s strong concern that Renzi will follow whatever Macron does.
“There was recently a discussion within the Socialist group and Italians faced accusations that Renzi is playing for Macron.”
And he appeared to heighten the rumours by meeting Ciudadanos leader Albert Rivera in Rome last month.
Mr Renzi has also appeared to be softening his left-wing stance, going for more moderate candidates in his country’s own election.
The MEP said: “The party which will emerge will be more centrist, with more Macron-inspired policies.”
Although the move has caused disquiet among the bloc’s socialists, Brussels’ leadership will be hoping Mr Renzi’s party can defy his poor polls in the Italian election and form a pro-European coalition with Silvio Berlusconi’s Forza Italia.
Italy’s election next month is causing panic in the bloc with the eurosceptic Five Star Movement leading in the polls.
Party leader Luigi Di Maio has vowed he will hold referendums on membership of the eurozone if he wins and his party has called for for a debate on the EU’s debt restructuring programme.
He said: “The post-voting scenarios are two – either the M5S rules the country or there will be chaos.
“I am confident, very confident. In these 25 days everything can change and we can reach the majority.”
However, the leader has recently scaled back on his promises, saying such referendums will be a “last resort”.
Some Italians are fed up with the EU for failing to help their country deal with with a growing number of migrants arriving from across the Mediterranean and for forcing it into austerity during the eurozone crisis that prolonged their economic stagnation.
Italy has a population size similar to Britain and France but its unstable political system.