Zambians began voting Tuesday in a presidential by-election pitting the ruling leftist Patriotic Front against the pro-business opposition United Party for National Development, dpa reported. PF candidate Edgar Lungu, 58, who is also justice and defence minister, was running neck-to-neck with the UPND's Hakainde Hichilema, 52. The by-election was called in the copper-rich southern African country after president Michael Sata died on October 28.