Colombians will cast ballots on Sunday in what is likely to be the first round of a presidential election, choosing between a leftist pledging to expand reforms begun by the current government, an ‌independent businessman promising a security crackdown and a right-wing senator seeking to become the country’s first female leader. Leftist Ivan Cepeda, a 63-year-old senator, is leading opinion polls, but looks likely to fall well short of the 50 per cent-plus support needed to avoid a June run-off.