Lima, Peru ? Ollanta Humala, a polarizing former army colonel who has shot to prominence by castigating Peru’s business and political leaders, led the first round of presidential balloting here Sunday, exit polls showed, and will face off in a May or June runoff against either former President Alan Garcia or former congresswoman Lourdes Flores.

The exit polls – taken as people left voting places – showed the leftist Humala winning 29 percent to 30 percent of the votes. Garcia, a centrist, had 26 percent, a slight advantage over Flores – a conservative free-market supporter – who had 25 percent.

Given the closeness of the race late Sunday, it was too early to put Garcia in the runoff with Humala.

The winner will replace outgoing President Alejandro Toledo, who cannot succeed himself.

A victory by Humala in the runoff election would continue the wave of leftist presidential candidates winning office in South America over the past year. It would also create another political ally for Venezuela’s Hugo Chavez, Washington’s chief headache in South America, after the election of Bolivia’s Evo Morales in December.