A demand has been made for a US senator to prove his fitness to serve or step down. This call comes after the senator's recent hospital stay. The demand was made by Kentucky's governor, who is a member of the Democratic Party.

The governor's request was made in a letter, following a statement from the senator's office. The statement was released on Monday, although its exact contents are not specified here. Further details about the situation and the letter are available from the source, which reported on the governor's demand and the senator's hospital stay.