Taiwan’s presidential candidates tried to rally support on Friday ahead of a vote that could impact the island’s foreign policy with regard to China and so, by extension, its relations with the United States.

Although the elections are mostly about economic issues, with the incumbent pointing at Taiwan’s solid growth rate last year and relatively low unemployment and his challenger citing mounting income disparity, Saturday will also be a referendum on the president’s conciliatory China policy.

Ma Ying-jeou, chairman of the Kuomintang Party, has tied the island’s economy ever closer to China’s. He welcomed Chinese tourists to Taiwan and enacted a free-trade agreement with the mainland in 2010 that reduced or eliminated tariffs on hundreds of goods. Most of Taiwan’s $124 billion worth of exports to China last year were electronic goods but there has been upsurge in agricultural sales across the Strait as a result of the tariff reductions.

China has entertained Ma’s overtures with largesse because it would rather have the Kuomintang in power than Tsai Ing-wen’s Democratic Progressive Party which is left of center but more adamant about Taiwanese independence.

Tsai has accused the president of undermining Taiwan’s de facto independence in favor of economic ties with the mainland. She has moved to the center in recent days to convince voters that she’s not a hardliner but China regards her election prospects warily nevertheless, especially after the United States announced a “pivot” to East Asia in order to contain China’s rise.

The Chinese still think of Taiwan as a renegade province. After the communists defeated the nationalist Kuomintang in China’s civil war in 1949, the party fled to Taiwan where it established a Republic of China that, until the early 1970s, was recognized as the true China by the United States.

The Americans remain Taiwan’s most important security partners up to this very day although there are voices in Washington calling for a suspension in military aid to the island in favor of more stable relations with the mainland.

The Obama Administration last year conceded to Chinese pressure when it canceled a fighter plane sale to Taiwan while the country had scheduled to retire some 70 percent of its fighter fleet over the course of this decade. China has significantly enhanced its air and missile strike capabilities at the same time, causing a security imbalance to develop across the Taiwanese Strait that America is unlikely to be able to mend with military force alone.

China seeks control of the Strait to enforce its claims to sovereignty over the South China Sea and keep foreign, i.e., American, naval forces out of that body of water. America isn’t giving up on Taiwan for this reason but has to pick its battles carefully as China emerges as the predominant power of East Asia. It may quietly hope for Ma’s reelection on Saturday and thus avoid a showdown with Beijing while a new generation of leadership prepares to take office there. It may see a need to assert itself in the face of what China perceives as Americans encroaching upon its natural sphere of interest. The question of Taiwanese independence would only complicate Sino-American relations while a fifth generation of leadership aims to consolidate power and authority in Beijing.

A similar dynamic plays out in the United States. President Barack Obama stands for reelection this year. If a shift in Taiwanese policy provokes a confrontation with China, that could leave him vulnerable to criticism from the Republican opposition that he’s “soft” on China whereas his challenger would vow to stand firm with America’s ally, Taiwan.