PERAI, Malaysia — Mahathir Mohamad, who led Malaysia for decades with dagger-sharp rhetoric and increasingly autocratic ways, is 92 and in frail health. But he wants his old job back.

To do it, Mr. Mahathir, already one of the world’s most durable political survivors, has engaged in yet another act of reinvention. This time, he is allying himself with opposition figures he once repressed in the name of beating his own former protégé, Najib Razak, whom he helped make prime minister in 2009.

The man who defined much of Malaysia’s political history is, in effect, standing before both the country as a whole and the new opposition allies he once persecuted and asking them to ignore the past. But he is certainly not apologizing.

“When it comes to the election, forget about everything and think only of winning,” Mr. Mahathir said at a recent campaign rally in Penang.