When Sam Rainsy lands in Phnom Penh on Friday morning to cheering crowds after almost four years of self-imposed exile, some will be waiting with bated breath that his 11th-hour return does not implode the most promising opposition merger in Cambodian history.

Given past animosity between Kem Sokha and Rainsy, who agreed on a union when it seemed unlikely that Rainsy would be little more than a symbolic leader-in-name from afar, reality is likely to set in for Sokha come Friday – if it hasn’t already.

For many Cambodians around the country, when asked for whom they are voting come July 28, the answer has long been not a party but one of two names: Hun Sen or Sam Rainsy.

This is in spite of the fact that Rainsy has not yet even been allowed to run as an official candidate for the Cambodia National Rescue Party.

Yet despite Rainsy’s grand return nine days out from the election, Sokha’s Human Rights Party faction has shown discipline and closed ranks around the CNRP before the election.

“We will not speak about the [Sam Rainsy Party] and HRP anymore. We will speak only about one word: the CNRP. Everybody including Kem Sokha and myself are so happy to see Sam Rainsy coming back,” former HRP spokesman and CNRP steering committee chairman Pol Ham said.

Current HRP president Son Soubert, HRP secretary-general Hing Sok San and other party members all echoed similar sentiments.

“They should combine forces … Kem Sokha has less pressure to go everywhere in the provinces [now that Rainsy is returning]. They can share together,” Soubert told the Post.

Despite these messages of unity, tensions between the parties are underlined by a number of past merger attempts that were aborted before they finally joined forces last year.

An attempt before the 2008 national election was foiled after Rainsy publicly criticised his HRP and Norodom Ranariddh Party coalition partners.

After the CPP’s election landslide, the HRP pushed again in 2009 to merge with the SRP if certain conditions were met – a new name for Rainsy’s eponymous party, joint decision-making and term limits for the party president.

That attempt failed, as did another in May 2011, when public bickering, including resistance from Rainsy to give up the party name, culminated in the leak of a 2007 phone conversation between Prime Minister Hun Sen and Kem Sokha.

At the time, SRP spokesman Yim Sovann said he believed the recording proved the HRP was a ruling-party puppet created to damage his party.

Ego clashes between Rainsy and Sokha have also been recurrent, with Sokha painting his counterpart as power-hungry and Rainsy slamming Sokha as “insincere” when previous merger attempts went belly-up.

“I think they’re both one-man bands in a way. … I think it’s extraordinary that these two guys have even cooperated this much,” eminent Cambodia historian David Chandler told the Post recently.

“Cooperating is not in their history or in their political style.”

But political analyst Chea Vannath argues that the time that was spent negotiating the various stumbling blocks on the path to the eventual merger will serve to keep the CNRP strong.

“It took a lot of time for them to be united. So, based on that, I’m sure they went through a lot of pros and cons … and being united here is for the sake of the strength of the opposition party,” she said.

“They have to, if not they go back to square one again.”

Another analyst, Lao Mong Hay, said the potential of the alliance to garner votes would stymie any factional splits until after the poll.

“Perhaps with a reduced majority [after the election] … [the CPP] might have to [pursue] one or two [leaders] from the opposition … that would be a challenge,” he said.

Unity is likely to prevail, he continued. Though some opportunists could see a CPP offer as the last chance to be in government, the history of ruling-party coalition partners sets a grim precedent.

“It would be end of [the HRP] if they defected.… I think they all realise the strategy of the CPP [will be] to split them,” Mong Hay said.

Still, with Rainsy’s comeback sure to help at the ballot box, political analyst Kem Ley predicts that the CPP is likely to try to engineer a split of the CNRP after the election.

“[The CPP] will find a way to [persuade] the CNRP to form a unity government to reduce the opposition movement. So the CNRP will divide into two groups,” he said.

Last week, it appeared that mixed messages were coming out of the CNRP camp on numerous issues related to Rainsy’s return, including decisions made about his return date.

“Even if they are united, Kem Sokha wants to be the leader of the party and wants to be prime minister if they win the election,” Ley said.

Cambodian Center for Human Rights president Ou Virak said that acceptance of term limits will be key for Rainsy if he wants to keep his alliance together.

“If any leader intends to [cling] to the position forever, I think they [are] bound to have internal division,” he said, adding that any successful attempt to lure CNRP legislators to the CPP after the election would violate election laws.

He also described Rainsy’s “curse” of seeing opposition politicians as a threat.

“Opposition politics belongs to Sam Rainsy and the Sam Rainsy Party, that is the mindset,” Virak said.

“[But Rainsy and Sokha] have similar beliefs.… The question will be whether these two people can … stand the tide and not look at the zero-sum game.… I don’t think [Rainsy has] realised that, unfortunately.”