Russia’s Central Election Commission (CEC) banned opposition politician Boris Nadezhdin on Thursday from the upcoming presidential election ballot. The commission made its decision after invalidating more than 9,000 signatures of support, leaving Nadezhdin short of the 95,000 valid signatures required to be listed on the ballot under Russian law.

Last week, state authorities accused Nadezhdin—one of the few opponents to Russian President Vladimir Putin—of submitting unspecific “errors” within his election paperwork.

A rare domestic critic of President Vladimir Putin’s ongoing war on Ukraine, Nadezhdin released a statement after the ruling saying that his campaign would appeal the decision of the CEC. Nadezhdin said that he disagreed with the commission’s findings, stating that he collected more than 200,000 signatures in support of his presidential bid. He claimed that he conducted his signature collection openly and honestly, despite the commission’s findings.

Although recent election polls in Russia show Nadezhdin trailing Putin by a substantial margin, Nadezhdin was the only candidate other than Putin to poll above 10 percent at any point in time—prior to Nadezhdin banishment from the race.

According to independent Russian outlet Sota.Vision, there was a heavy police presence outside of Thursday’s CEC hearing. Rights groups have expressed increasing concern over the deterioration of Russia’s democratic institutions in recent years. In recent months, Russia’s treatment of foreign journalists, including the jailing of Wall Street Journal reporter Evan Gershkovich and Radio Free Europe reporter Alsu Kurmasheva, have drawn condemnation. Russia’s ongoing imprisonment of opposition leader Alexei Navalny also remains a point of international contention.

Nadezhdin, for his part, remained undeterred in his bid to unseat Putin. He said that his decision to run in the 2024 presidential race was the most important political decision of his life.