Brazilians are heading to the polls to vote in the presidential election Sunday. President Dilma Rousseff faces a challenge from Marina Silva, who served as environment minister under President Luiz Inácio Lula da Silva before resigning in 2008. She became a candidate in August after her running mate died in a plane crash. Marina Silva grew up in the Amazon rainforest and fought its devastation alongside rubber tapper Chico Mendes. Her supporters say she would become the world’s first “green” president. But critics worry that as an evangelical Christian, she would implement right-wing social policies. They also note her chosen running mate has ties to agribusiness.