The rise of the opposition Cambodia National Rescue Party (CNRP) ahead of a general election next year is being watched closely by neighbouring Vietnam.
At commune elections earlier this month - a commune is a local government below the levels of province and district - the ruling Cambodian People's Party (CPP) won only 1,156 communes, a 28 per cent fall. The CNRP, on the other hand, managed to win 489, a 12-fold increase.
This reflects the continuing decline of the CPP since the 2013 general election, in which it lost 22 National Assembly seats, bringing its percentage of seats to the lowest since 1998.
This raises an important question for Vietnam, a country the CNRP has maintained a hostile attitude towards: How should Hanoi deal with the CNRP's possible rise to power in the future?
Relations with Cambodia have important implications for Vietnam. In the late 1970s, the Khmer Rouge's armed harassment posed a substantial threat to Vietnam's security. Hanoi's subsequent military involvement in Cambodia in the 1980s seriously constrained its efforts to revive the war-torn economy.
Ever since peace was restored to Cambodia in 1991, relations between the two countries have flourished. However, the possible rise to power of an anti-Vietnam CNRP threatens to raise the spectre of the past, which Hanoi feels uneasy about.
Vietnam has not yet established a formal communication channel with the CNRP. Such a lack of interaction limits Hanoi's ability to maintain stability in bilateral relations with Phnom Penh, should the CNRP come to power.
There are three key reasons for Vietnam's hesitation in setting up contacts with the CNRP.
First, the CNRP and its leadership have traditionally maintained a hostile stance towards Vietnam. CNRP leaders, especially former party president Sam Rainsy, frequently criticised Vietnam over territorial and historical issues.
He once even removed a marker on the Vietnam-Cambodia border to protest against the Hun Sen government's settlement of border disputes with Vietnam.
As a consequence, there is a deep distrust between Vietnam and CNRP officials, which prevents them from talking to each other.
Second, the Vietnamese government may be concerned that establishing ties with the CNRP will upset the CPP and its leadership, especially Prime Minister Hun Sen, with whom Vietnam has maintained close ties.
Third, Vietnam may believe the CPP is likely to win the 2018 general election. Mr Hun Sen has showed that he is determined to maintain the CPP's power by declaring there will be a "civil war" if it is defeated. As such, Vietnamese leaders may assume it is not yet necessary to establish ties with the CNRP.
HOSTILITY AN ELECTION TACTIC? However, the trends emerging from the recent commune elections as well as the 2013 general election suggest that it is time for Vietnam to rethink its position.
For starters, although the CNRP and its leaders have been hostile to Vietnam, it may be just an electoral tactic to exploit anti-Vietnamese sentiment.
As Vietnam is important to Cambodia's security and economic well-being, it is highly likely that if the CNRP does come to power, it will adopt a more balanced and neutral stance on Vietnam. After all, Vietnam was Cambodia's third-largest trade partner and fifth largest foreign investor last year.
Whether this happens, however, depends on the CNRP's understanding of Vietnam's intentions and positions, a development which is constrained by the lack of communication between the Vietnamese authorities and the party.
As well, although the CPP and Mr Hun Sen may be uncomfortable if Vietnamese officials come into contact with the CNRP, it is absolutely normal for a given government to have ties with different political parties of another country. China, which is also a close partner of the CPP, has established contacts with the CNRP. The latter's leaders have paid visits to China, and the Chinese ambassador has been to Phnom Penh, meeting CNRP leaders after the 2013 election. Yet, China's relations with Cambodia, as well as the ties between the CPP and the Communist Party of China, remain intact. Therefore, Vietnam should not be oversensitive about the CPP's reactions.
Finally, Vietnam should not place all its bets on the CPP. Emerging trends from the recent elections as well as other electoral dynamics, such as Cambodia's demographics, urban-rural voting patterns, the rise of social media, the CPP's governance performance, and the CNRP's electoral tactics, suggest that the prospect of the CNRP winning future general elections should not be underestimated.
As the saying goes, "keep your friends close, and your enemies closer". It is high time now for Vietnam to establish official contacts with the CNRP to exchange views, build mutual trust, and set up working mechanisms to better prepare itself for future possible power shifts in Cambodia.
• Lee Hong Hiep is a research fellow at ISEAS - Yusof Ishak Institute. S.E.A. View is a weekly column on South-east Asian Affairs.