BUCHAREST Reuters) -Romanians vote on Sunday in a presidential election run-off that pits a hard-right eurosceptic against a centrist independent, and where the outcome could have implications for both the country's struggling economy and EU unity. Hard-right nationalist George Simion, 38, who opposes military aid to neighbouring Ukraine and is critical of European Union leadership, decisively swept the first presidential election round, triggering the collapse of a pro-Western coalition government. Centrist Bucharest mayor Nicusor Dan, 55, who has pledged to clamp down on corruption, is staunchly pro-EU and NATO, and has said Romania's support for Ukraine is vital for its own security against a growing Russian threat.