The Holy See had yet to respond to the nomination of Laurent Stéfanini, which was delivered in January, French newspaper Le Monde reported Thursday.
Vatican experts say they believe the delay in approval is effectively a rejection of Stéfanini, but the Vatican itself won’t comment.
"Any host government has the right to grant agrément or refuse it for their own reasons," the Rev. Thomas Rosica, a Vatican spokesman, told the Washington Post.
Stéfanini, a practicing Catholic, had served four years as the second-highest ranking French diplomat to the Holy See before becoming head of protocol in President François Hollande’s government.
Even the Archbishop of Paris, Cardinal André Vingt-Trois, reportedly supported the appointment.