By Luiza Ilie, Libby George and Gergely Szakacs BUCHAREST/LONDON (Reuters) -Romanian centrist Nicusor Dan may have defied the odds to win the presidency, but now he faces an even more daunting task: forming a government that can implement years of painful austerity - and revenue-raising measures - to tame Europe's widest fiscal deficit.

As a member of the EU and one of the easternmost members of the NATO military alliance, Romania plays a pivotal role in Western security infrastructure.

Thousands of people gathered in Romania’s capital on Friday for a pro-European Union march. It came a week before the final vote of a closely watched presidential election that pits a hard-right nationalist front-runner against the capital’s pro-EU mayor.