Georgia, a strategically-located republic at the center of the Caucasus, plunged into political crisis on Sunday as the ruling party celebrated victory in a pivotal election that the pro-Western opposition declared as falsified, vowing to boycott the new parliament.

The shaky situation further polarized a political struggle between Georgian Dream, which has governed Georgia for 12 years, increasingly steering it away from its decades-long path to join NATO and the European Union, and the four political groups that aimed to keep it moving toward the West.

The crisis will likely push Georgia further away from the West, with European observers criticizing the conduct of the election on Sunday. Zlatko Vujovic, the head of the European Network of Election Monitoring Organizations, characterized the election as “not good.”

“They were not conducted in the proper way as should be expected from a country that has a E.U. candidate status,” Mr. Vujovic said at a briefing with journalists.

Critical violations included violence against opposition members, voter intimidation, smear campaigns targeting observers, and extensive misuse of administrative resources, he said.

The Election Administration of Georgia, the body that oversees elections in the country, reported on Sunday that the ruling party garnered more than 54 percent of the vote with the four main opposition groups receiving 37.5 percent. That means that Georgian Dream will have 89 seats in Parliament with the remaining 61 occupied by the opposition.