Moldovans were on track to clear a key hurdle toward joining the European Union in a set of votes on Sunday that may help break the Kremlin’s decades-long grip on the country.

More than 32% of voters participated in a referendum to join the EU as of 15:00 local time on Sunday, just shy of a one-third threshold required to validate the ballot, the country’s Central Electoral Commission said. The nation is also holding a presidential election, in which Maia Sandu is favoured to win a second term.

The stakes are high in the former Soviet republic as the pro-EU government faced what it…