Updated

Hungary's Socialist Party has chosen Attila Mesterhazy as the prime ministerial candidate of the alliance of five left-wing opposition parties for the upcoming parliamentary elections.

Mesterhazy was endorsed by 99.7 percent of party delegates on Saturday to lead the alliance which also includes two former Socialist prime ministers, Ferenc Gyurcsany and Gordon Bajnai, who have formed their own parties.

The April 6 elections are being held under a new system which critics say heavily favors the governing Fidesz party led by Prime Minister Viktor Orban.

Elections will include only one round of voting instead of two, cut to the number of legislators nearly in half and significantly restrict campaign ads.

Mesterhazy, who will turn 40 years old on Thursday, has led the Socialist Party since July 2010.