Bulgarian Prime Minister Boyko Borisov arrives at a European Union leaders summit in Brussels, Belgium December 14, 2018. REUTERS/Piroschka Van De Wouw

SOFIA (Reuters) - Bulgaria’s ruling center-right party GERB on Monday dropped plans to revise the election code after they prompted the main opposition Socialist Party (BSP) to walk out of parliament.

The BSP said on Sunday that fair elections could not be guaranteed in Bulgaria following the revisions, voted through after a marathon, 14-hour session last Thursday.

The move by the BSP, which holds 79 of the 240 seats in parliament, threatened to undermine the assembly’s ability to pass legislation by making it harder to reach a quorum.

The amendments would have raised the threshold for preferential voting in elections, widened the use of machine voting as opposed to paper ballots, and changed the way the election commission operates.

Prime Minister Boyko Borisov, whose GERB party has 95 seats, said a new election commission would be formed “in a clear and transparent way” before the European Parliament elections in May.

The BSP, heir to Bulgaria’s once-mighty Communist Party, reacted cautiously to Borisov’s announcement.

“You will only see us back in the chamber when we have seen real action by GERB,” said BSP deputy Tasko Ermenkov.