July 8, 2018: An election poster with images of Heng Samrin, Honorary President of the Cambodian People's Party, and Prime Minister Hun Sen, in Siem Reap.

Cambodia's general election on July 29 has become a proxy theater for competition between China and Japan as the two vie for influence in the Southeast Asian state.

As Phnom Penh's largest foreign investor and economic benefactor, the world's second-largest economy has donated $20 million in polling booths, laptops, computers and other equipment to the National Election Committee, an agency that supervises elections, according to the Associated Press. Tokyo, also one of Cambodia's top donors, has provided over 10,000 ballot boxes worth $7.5 million, Reuters reported.

Those contributions aren't surprising since both Asian heavyweights hold historically deep ties with the frontier economy. But Tokyo, concerned about Beijing's rising influence across Southeast Asia, is likely acting with strategy in mind.

"Japan’s economic footprint is starting to be dwarfed by the scale of Chinese investment in the country, through Belt and Road projects, and Chinese political influence," said Champa Patel, head of the Asia-Pacific program at London-based policy institute Chatham House. For Japanese Prime Minister Shinzo Abe, "maintaining relations with Cambodia will be to act as a counterweight to Chinese influence in the country and the wider region," she continued.

Chinese President Xi Jinping's administration has offered Cambodian Prime Minister Hun Sen's government billions in development assistance and loans through bilateral frameworks and the continent-spanning infrastructure program known as Belt and Road. That, in turn, has produced a flood of Chinese commercial ventures in the country, including economic zones, casinos and industrial parks.

Beijing's economic leverage is also believed to have translated into political clout: During a 2016 ASEAN meeting, Phnom Penh was widely seen as acting as an agent of China when it blocked mention of an international court ruling that rejected Beijing's territorial claims in the South China Sea in the group's official communique.