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.