PHNOM PENH (Reuters) - Cambodia’s main opposition party has given up hope of escaping a ban when the Supreme Court rules on Thursday on a suit brought by the government of authoritarian leader Hun Sen, a senior leader said.

FILE PHOTO - Cambodian opposition leader Sam Rainsy delivers a speech to members of the Cambodia National Rescue Party (CNRP) at a hotel in metro Manila, Philippines June 29, 2016. REUTERS/Romeo Ranoco/File Photo

The government called for the ban after arresting Cambodia National Rescue Party (CNRP) leader Kem Sokha on Sept. 3 and charging him with treason for an alleged plot to take over the Southeast Asian country with help from the United States.

Hun Sen’s opponents say the charges are politically motivated to eliminate Kem Sokha from next year’s election so the strongman, who is currently the world’s longest serving prime minister, can extend his more than 32 years in power.

The judge who heads the Supreme Court, Dith Munty, is a member of the permanent committee of the ruling Cambodia People’s Party (CPP) and a longtime Hun Sen loyalist.

“There is no chance whatsoever for CNRP to escape dissolution,” said Mu Sochua, a deputy of Kem Sokha who fled abroad last month saying she feared arrest in a widening crackdown by the government.

“November 16, 2017 will mark the end of true democracy in Cambodia,” she told Reuters, adding that the ruling party would face local condemnation and possible international sanctions.

Hun Sen, a former Khmer Rouge commander, has held power since 1985 by intimidating and dividing his enemies and through legal proceedings that have occasionally led to political bans on rivals at critical moments.

Next year’s election was shaping as possibly the biggest challenge to Hun Sen’s leadership, after his opponents unified behind the CNRP.

VETERAN RETURNS

Former CNRP leader Sam Rainsy, who fled to France in 2015 to escape a jail term for defamation, announced on Wednesday he was returning to the party that he quit in February over fears his membership would lead to it being banned.

The veteran opponent of Hun Sen said the party would be dissolved anyway so his membership now made no difference.

A government official said Sam Rainsy’s return would only provide further justification for dissolving the party.

“He is not mature. He has no political philosophy and doctrine, but only anger and hatred,” Huy Vannak, undersecretary of state at the Interior Ministry, told Reuters. He also noted that the CNRP had not defended its position in court.

A party lawyer, Sam Sokong, said there had been no point because the case was politically motivated.

Western countries have condemned the government’s crackdown on the opposition, civil rights groups and independent media and have called for the release of Kem Sokha to allow credible elections next year.

U.S. President Donald Trump’s senior Asia aide expressed “strong concerns” to Cambodia’s government about the detention of Kem Sokha and restrictions on civil society and the press on Tuesday.

Hun Sen has brushed off Western criticism, though he also lauded Trump as a kindred spirit this week and urged him to rein in subordinates critical of Cambodia. Hun Sen is also increasingly close to China, Cambodia’s biggest donor.

The main evidence presented against Kem Sokha is a video from 2013 in which he talks about a plan to gain power with the help of Americans. He says he was talking about democratic politics.

Cambodia’s capital, Phnom Penh, was calm on Wednesday. But metal barriers were set up outside the gold-embellished Supreme Court and police have been told to watch for trouble.

Few in the capital wanted to give any opinion on the ruling or the possible verdict.

“The court will decide. We cannot do anything,” said Kou Menglay, a taxi driver.