President Salome Zourabichvili of Georgia said on Saturday that she had vetoed a bill on foreign influence that has sparked protests and plunged the nation into a political crisis, threatening to derail its pro-European aspirations in favor of closer ties with Russia.

Georgia’s Parliament, which passed the draft law in three readings, is widely expected to override the veto. The ruling Georgian Dream party, which introduced the proposed legislation, can turn it into law as early as May 28, when the Parliament will be in session again.

Mrs. Zourabichvili called her veto “symbolic,” but it still represented another step in the political conflict between the country’s pro-Western opposition, which Mrs. Zourabichvili supports, and the Georgian Dream party, which has been in power since 2012.

The crisis has highlighted the highly polarized nature of Georgia’s political life. It has called into question the country’s pro-Western course, which is enshrined in its Constitution, as American and European officials threatened to downgrade ties with the country and impose sanctions on its leadership if the law were to be finalized and protests against it were crushed.

Georgia, a mountainous nation of 3.6 million in the middle of the Caucasus, once was a pro-Western trailblazer among former Soviet states. If it were to turn away from the West in favor of a closer relationship with Russia, the geopolitics of the whole region could change, because of the country’s central geographical position there.

The draft law that triggered the crisis bears an innocuous-sounding name: “On Transparency of Foreign Influence.”