SAN ANTONIO — Rick Perry, the longest-serving governor of Texas and an unsuccessful Republican presidential candidate last year, announced on Monday that he would not seek another term but would instead “pray and reflect and work to determine my own future path.”

“The time has come to pass on the mantle of leadership,” Mr. Perry told a crowd of supporters in a cavernous heavy equipment dealership here. “Today, I am announcing I will not seek re-election as governor of Texas.”

As for what happens after his term is over in 18 months, he said he would “announce any future considerations in due time,” almost certainly an allusion to the possibility of a White House bid in 2016, though he made no direct reference to it. Mr. Perry has indicated regret over entering the presidential race relatively late in the process and has said that back trouble and a lack of sleep contributed to his gaffe-plagued campaign.

But it is an open question whether an earlier start and better health would make a difference for Mr. Perry, should he try to run again. Mr. Perry faces some daunting challenges. First, he would have to convince Republican primary voters that he is not the lightweight who could not recite the third of three federal agencies he would eliminate and blurted out, “Oops.”