OKLAHOMA CITY (AP) — An attorney seeking to stop a special election for a soon-to-be-vacant U.S. Senate seat in Oklahoma has refiled his lawsuit in federal court.

Enid attorney Stephen Jones argues the special election called by the governor to fill U.S. Sen. Jim Inhofe's seat is improper because the seat has not yet been formally vacated.

Inhofe, 87, the ranking Republican on the Senate Armed Services Committee, announced earlier this year that he plans to resign in January, just two years into his six-year term. He quickly endorsed his longtime chief of staff, Luke Holland, in the race to replace him.

Inhofe also submitted an "irrevocable pledge" to the Oklahoma Secretary of State's Office on Feb. 28, triggering a new state law that allows the governor to set special election dates that coincide with Oklahoma's regularly scheduled primary, runoff and general election dates. Gov. Kevin Stitt set the special election dates on March 1.

But Jones argues in his filing that the 17th Amendment to the U.S. Constitution doesn't permit a special election until the senator vacates the office.

The Oklahoma Supreme Court last month declined Jones' request to assume original jurisdiction in the case. Jones refiled the case in federal court on Friday.