Cambodia’s Supreme Court on Thursday dissolved the main opposition party, paving the way for Prime Minister Hun Sen (pictured above) to stand for elections next year without any challengers, The New York Times reported.

The Supreme Court ban on the Cambodia National Rescue Party, at the government’s request, comes after the arrest of its leader, Kem Sokha, for treason, Reuters reported. He is accused of plotting to take power with American help.

“It is a serious crime, so the party will be dissolved according to Article 38 of the Law on Political Parties,” Dith Munty, the Chief Judge of the Supreme Court, said according to The New York Times. The judge is a close associate of Hun Sen. There is no right to appeal.

With the main opposition party banned, Cambodia has essentially become a one-party state, the United Nations said, according to the report. Several opposition officials are now stripped of their parliamentary seats. The opposition denied the charges of sedition and said it was only working to win the elections.

Soon after the ban, the United States stopped election support for Cambodia with a promise of more “concrete steps”, while the European Union threatened vital trade preferences. China, however, said it supported Cambodia’s government and will stand behind the former Khmer Rouge commander, who is one of Beijing’s most important allies after more than three decades in power.