Croatians cast ballots in a presidential vote on Sunday that could weaken the ruling conservatives just as the country takes the helm of the European Union's rotating presidency. The pre-Christmas poll, likely to be decided in a January 5 run-off, has evolved into a tight race between conservative incumbent Kolinda Grabar-Kitarovic and front-running rivals on the right and the left. Grabar-Kitarovic has been president since 2015 with backing from HDZ, the centre-right party that has led Croatia for most of its independence since 1991.