A top Romanian court has validated the first round of a presidential race in which a far-right outsider emerged as the frontrunner, plunging the country into a week of turmoil amid allegations of electoral violations and Russian meddling.

Romania's Constitutional Court on Monday validated the shock first-round result in the country's presidential election, setting the stage for a run-off vote on Dec. 8 that could upend its pro-Western orientation and undermine backing for Ukraine.