People in Poland were casting ballots for president on Sunday, with incumbent Bronislaw Komorowski expected to win but fall short of the 50 per cent threshold needed to avoid a run-off, dpa reported. Komorowski, of the centre-right Civic Platform party, has seen his rating dip from above 50 per cent a few months ago to just below 40 per cent in the latest public opinion poll by broadcaster TVN. His main challenger, Andrzej Duda of the conservative Law and Justice party, is hovering near 30 per cent, meaning a second round of voting will likely take place on May 24. A former defence minister and parliamentary speaker, Komorowski has been president since 2010. The vote on Sunday is seen as a bellwether ahead of parliamentary elections this autumn.