19:38 BST
Sarah Rainsford
Eastern Europe correspondent, reporting from Bucharest
Image source, Getty ImagesWhat we have so far are exit polls, not a final result by any means.
But the gap it shows between the two candidates is large, and it may be hard for George Simion to catch up.
The big thing to watch for now is the vote by the diaspora. More than a million Romanians living abroad are registered to vote and there are no exit polls for them. But we know they voted in big numbers for Simion in the first round.
Turnout was significantly higher this time – 64.71%, not 53% as in the first round – and the number of people voting in urban areas was also up.
That may well have benefited Nicusor Dan, whose voting base is stronger in cities. But none of this has stopped George Simion from celebrating.
He came out on to the steps of parliament tonight to declare: “I’m the new president of Romania” and went on to describe what he would do in the post.
His supporters, including a group of foreign guests, then danced to YMCA, blasted from the speakers, Trump-style.
One of them, leaving the peculiar party, told the BBC he was convinced the exit polls – based on questioning voters at polling stations – do not represent the real vote. He told us his candidate would ultimately emerge as the winner.