Hungary’s Prime Minister Viktor Orban has lost his super majority after a by-election was won by independent candidate Zoltan Kesz.
The “super majority” allowed the prime minister to pass a new constitution and other laws without support of the other parties in parliament.
The by-election was triggered by Fidesz’s Tibor Navracsics, who won the seat in April, being made a EU commissioner.
Mr Kesz was an independent candidate but had the support of Hungary’s left-wing opposition parties, which were heavily defeated by Fidesz in 2010 and have struggled to recover.
Mr Orban has been dogged by allegations of corruption during his five years in office and has seen his popularity slump since attempting to pass a controversial internet tax, which was later scrapped.
Other unpopular laws, including a ban on shops opening on Sundays and the introduction of increased road tolls, have contributed to a significant dip for Fidesz in opinion polls.