Opposition deputy leader Kem Sokha has promised to retire from politics if his Cambodia National Rescue Party does not win the province of Kampong Cham in the 2018 national elections.

The CNRP deputy president made the comments in a speech in Kampong Cham on Saturday, during which he also urged other parties that intend to field candidates in 2018 to join forces with the country’s main opposition.

“I dare to say that we will win because the [CNRP] is still keeping to its position and not turning away. I want to call on all Khmer patriots in all political parties to consider the national democratic interest and unite with the [CNRP],” he said.

“Because [the ruling Cambodian People’s Party] knows our stance is to win and to guide the country to change the leadership … [CPP politicians] are angry,” he added.

Sokha’s comments came just days after Prime Minister Hun Sen told a gathering of Cambodian expatriates in the US that the CNRP had “a plan to topple” the government “through people power” at the last election in 2013.

Hun Sen quoted Sokha as saying that if the premier did not step down he would be forced out as a “final measure”.

Hun Sen then reportedly told Sokha that he was fortunate not to have attempted to overthrow him as it would have been Sokha’s “funeral day” if he had.

The rhetoric comes amid a fractured detente between the two major political parties, known as the culture of dialogue. Since it was announced in July 2014, the purported cooling of rhetoric has been marred by arrests of CNRP supporters and members, and of a Sam Rainsy Party senator, Hong Sok Hour.

CPP spokesman Sok Eysan yesterday dismissed Sokha’s comments, saying the CNRP was using the sentencing of CNRP activists as a political tool to gain support, while in fact the 15 CNRP members and supporters given lengthy sentences earlier this year had broken the law and were punished accordingly by the courts. The CNRP and rights groups, however, say the hearings were politically motivated and did not meet the minimum legal standards for a fair trial.

Speaking to Australia’s ABC Radio on Friday, CNRP president Sam Rainsy called Hun Sen’s Cambodia a “dictatorship”, a term the ruling party warned the opposition against using under the new culture.

“This is just a fact as observed by everybody, including the civil society, who deplores the continuous shrinking of Cambodia’s democratic space, especially the restriction of freedom of expression,” he said yesterday.

Yesterday, Rainsy maintained that the culture of dialogue wasn’t on shaky ground.

“It has been designed not just for Hun Sen and Sam Rainsy, nor for only the CPP and the CNRP, but for the long term . . . It’s a must if we want to strengthen democracy and to put an end to the culture of violence in our country.”

ADDITIONAL REPORTING BY CHEANG SOKHA AND ALICE CUDDY