How to Set GPTM Interrupt Priority?

I am working with the TM4C129XNCZAD processor on the "mikromedia 5 for tiva" evaluation board from Mikroelectronica. I am trying to set the interrupt priority level of a few general purpose timers. The TM4C129XNCZAD datasheet does not talk about this specifically in the GPTM section. I need to be able to do this without tivaware because I am using the "mikromedia 5 for tiva" evaluation board. I have already tried adjusting the NVIC - PRI registers (Pg. 169) but it does not seem to make any difference in my program. What should I try?