NASHVILLE (AP) — Attorneys are asking the U.S. Supreme Court to stay the looming execution of a convicted child killer after the Tennessee Supreme Court and governor decided against a delay.

In a filing Tuesday, federal public defender Kelley Henry and attorney Carl Gene Shiles Jr. wrote that Billy Ray Irick should get a stay of Thursday's scheduled lethal injection while a challenge of the state's protocol continues on appeal.

The state Supreme Court wrote Monday that Irick's attorney didn't meet the burden of proving the lawsuit challenging Tennessee's new three-drug cocktail is likely to succeed. Gov. Bill Haslam said Monday he won't intervene.

Protesters demonstrated Tuesday, urging Haslam to stop the execution.

Irick would be the first inmate Tennessee has executed since 2009. He was convicted of the 1985 rape and murder of a 7-year-old Knoxville girl.