BUCHAREST—On a recent day, nationalist politician Călin Georgescu made his way through a crush of people to enter a district court in Romania’s faded belle epoque capital to argue that he should be free to run in coming presidential elections.

Romania's top court upheld a decision to ban far-right candidate Calin Georgescu from standing in a presidential election rerun in May, it said on Tuesday, leaving his allies with four days to find a replacement.

A top Romanian court has rejected an appeal by far-right politician Calin Georgescu to lift a ban on his candidacy in the presidential rerun