Sen. Ron Johnson is launching an investigation into former President Biden's health, he told Axios. Why it matters: The news of Biden's cancer diagnosis as well as new revelations about the White House's efforts to hide the former president's deteriorating health has reignited attacks from the GOP about Biden's fitness to carry out the duties of commander in chief.

Former President Joe Biden has been a fixture in Washington since 1972, starting with his career in the Senate, followed by a combined 12 years in the White House, first as vice president and later commander-in-chief.

The news of Joe Biden's prostate cancer diagnosis has raised questions about why the disease wasn't detected earlier.