Bulgaria has the green light to join the euro next year and become the 21st member of the European Union's currency union.

The European Union gave Bulgaria the green light to join the euro, but political ructions in Sofia threaten to torpedo its accession.

SOFIA, Bulgaria — Bulgaria is close to realizing its decades-old goal of joining the euro currency union and deepening ties with the more prosperous countries of Western Europe. But the government faces a populist backlash against the shared currency on the eve of a key decision by European Union authorities.