Romania's electoral body has rejected the candidacy of controversial far-right politician Diana Sosoaca in the presidential election rerun in May, but approved George Simion, the leader of the country's most popular far-right party.

Former Romanian Prime Minister Victor Ponta joined the race for May's presidential election re-run on Wednesday as the hard right worked to ensure they had a candidate in the contest after the ban on pro-Russian Calin Georgescu threw the vote wide open.

Controversial politician Diana Sosoaca, who was barred by a top court from entering last year's presidential election, raises her hand wearing boxing gloves speaking outside the country's electoral authority after she registered an unlikely bid to enter the May rerun in Bucharest, Romania on March 13. (AP)

Romania's populist far-right politician George Simion is making his bid for the country's presidential election rerun in May as he seeks to rally nationalist voters after a controversial frontrunner was barred from the race last year.

The leader of Romania’s largest far-right party will be allowed to take part in May’s presidential election after the previous frontrunner, whom he backed, was barred from the race.