WASHINGTON—Top Republican lawmakers are calling on Veterans Affairs Secretary Eric Shinseki to fire his chief of staff for approving two training conferences that led to $762,000 in questionable spending.

The department had already accepted the resignation of an assistant secretary in response to a critical inspector general's report.

But Rep. Jeff Miller and Sen. Richard Burr say accountability begins at the top and that the department's chief of staff, John Gingrich, bears ultimate responsibility because he approved the conferences in Orlando, Fla. They said in a letter to Shinseki that a message must be sent to all VA employees that the "perfunctory execution" of important responsibilities is inexcusable.

Federal investigators found the conferences were held to fulfill valid training needs, but that some of the expenses were unnecessary or wasteful.