Donald Trump worried that Rudy Giuliani might lack the stamina to fulfill the duties of secretary of state, according to a report.

Once a leading candidate to be America’s top diplomat, Giuliani fell out of favor, in part because Trump began to question the 72-year-old’s fitness, according to the Wall Street Journal, which cited an unnamed transition official.

Giuliani strongly disagreed, telling the paper: “My stamina is unbelievable.”

The former mayor, who was one of the billionaire’s fiercest loyalists on the campaign trail, has said he has so far passed on two cabinet postings in the Trump administration, without specifying which posts.

Rex Tillerson, the CEO of ExxonMobil, was announced Tuesday as Trump’s choice to be secretary of state.

In his younger days, Giuliani had plenty of stamina to work with Trump in some pretty unexpected ways: