AUSTIN, Texas -- A Texas man set to die this month is at the center of another push for clemency in the U.S., this time backed by several GOP lawmakers and bestselling author John Grisham , who say a father’s 2002 conviction for killing his infant daughter deserves a second look.

Their pleas to spare Robert Roberson, who is set to die by lethal injection on Oct. 17, comes after Missouri and Oklahoma carried out executions last month over calls to grant two condemned men lesser punishments, underlining how rare clemency remains for death row prisoners. The cases highlight one of a governor's most extraordinary powers — whether to allow an execution to proceed.

In Texas, the state's parole board and Republican Gov. Greg Abbott have yet to weigh in on Roberson, whose defenders say was convicted based on faulty scientific evidence. In Missouri, the execution of Marcellus Williams on Sept.

24 reignited calls for transparency in the decision-making process after a prosecutor and the victim's family had urged Republican Gov. Mike Parson to reduce the sentence. Parson said multiple courts had not found merit in Williams' innocence claims.

“Capital punishment cases are some of the hardest issues we have to address in the Governor’s Office, but when it comes down to it, I follow the law and trust the integrity of our judicial system,” Parson said in a statement before Williams’ execution. Clemency is the process that allows a governor, president or independent board to less.