NASHVILLE (AP) — The Tennessee Attorney General says an inmate's scheduled execution next week should proceed, saying there's no chance the man's constitutional challenge of the state's lethal injection method will succeed.

The Tennessean reported Attorney General Herbert Slatery filed the argument Thursday with the courts. The filing follows a request by 59-year-old inmate Billy Ray Irick that the state Supreme Court delay execution plans until the challenge is resolved.

Irick, who advocates say has severe mental illness, was convicted in 1986 of the rape and murder of a 7-year-old.

He is one of 33 death row inmates appealing the challenge of whether the state's three-drug execution method is constitutional after losing the case last month. However, no court could hear the appeal before Irick's execution set for Aug. 9.