U.S. President Donald Trump’s allies on Monday used Joe Biden’s cancer diagnosis to stoke a growing row over whether the Democrat and his team covered up concerns about his health while in office.

While Trump expressed sadness after Biden was found to have an aggressive form of prostate cancer, his Vice President JD Vance said that “we really do need to be honest” about Biden’s fitness.

Trump’s son Don Jr. questioned whether there had been a “cover up.”

Biden’s health was already in the spotlight before his diagnosis with “aggressive” prostate cancer, thanks to a new book on the subject that comes out this week.

The book, “Original Sin” by CNN journalist Jake Tapper and Alex Thompson of Axios, alleges that Biden’s White House covered up signs of his physical decline while he was campaigning against Trump for a second term.

Biden, 82, was the oldest president in U.S. history when he left office in January. He dropped out of the 2024 election after a disastrous debate performance against Trump in June.

Trump meanwhile is the oldest president to be inaugurated, at 78.

Joe Biden expressed his gratitude for the words of support that have poured in from across the world, including a private letter from Britain’s King Charles, after the former US president announced his cancer diagnosis on Sunday.

“Cancer touches us all,” Biden wrote on social media on Monday morning. “Like so many of you, Jill and I have learned that we are strongest in the broken places. Thank you for lifting us up with love and support.”

On Sunday, Biden’s office disclosed that he was diagnosed with an aggressive form of prostate cancer that has spread to his bones.

Biden’s team have consistently denied there was any effort to conceal fears about his health.

“We really do need to be honest about whether the former president was capable of doing the job,” Vance told reporters after visiting Pope Leo XIV in Rome.

“You can separate the desire for him to have the right health outcome with a recognition that — whether it was doctors or whether there were staffers around the former president — I don’t think he was able to do a good job for the American people.”

Vance, 40, added: “In some ways, I blame him less than I blame the people around him.”