"If I was an American citizen I wouldn't hesitate to vote for Obama," he told a radio interviewer on Wednesday.
While it is hardly surprising that Ayrault, a Socialist, would support the Democrat candidate in a US election, prudence normally restricts politicians from making such remarks given the possibility they will end up having to deal with their Republican rivals.
Ayrault is not however the first French minister to offer public support for Obama in his neck-and-neck battle with Republican Mitt Romney.
On Tuesday, Bernard Cazeneuve, the European affairs minister, said: "As far as I'm concerned, I totally support it (Obama's re-election) and I would be astonished if the government had any other wish."
President François Hollande was less explicit when he was asked who he would support during a visit to New York at the end of last month, restricting himself to a rhetorical: "Who would you think?"