COLOMBO, Sri Lanka (AP) — Long lines formed in the capital Thursday and voter turnout was heavy in Sri Lanka’s Tamil heartland as President Mahinda Rajapaksa faced his toughest electoral challenge in years, with a former ally trying to unseat the leader who crushed a brutal Tamil insurgency and amassed immense power for himself and his family. Some voters were prevented from casting ballots in the Tamil-dominated north, according to the Center for Monitoring Election Violence, and there were a handful of incidents of isolated violence, but no injuries were reported. Results were expected to be announced Friday.