Officials in Washington and Beijing seemed relieved when Taiwan’s moderate Kuomintang took control of the legislature earlier this year and Ma Ying‐​jeou was elected president. But that optimism is fading fast as China’s lack of meaningful concessions has undermined Mr. Ma’s political position. It’s becoming clear that the Taiwan side has done all it can so far. The next steps will depend on Beijing.

Voters in Taiwan have certainly set the stage for progress. Mr. Ma’s commitment to promoting stability and cooperation with the mainland is calibrated to reduce the cross‐​Strait tensions that reached alarming levels under former President Chen Shui‐​bian and his pro‐​independence Democratic Progressive Party. The conventional wisdom in both the U.S. and China is that the KMT’s electoral triumph was a repudiation of the DPP’s assertive, pro‐​independence policies.

That assessment is undoubtedly oversimplified, however. The needlessly aggressive posture of Mr. Chen’s government certainly played a role in his party’s defeat, but discontent about Taiwan’s underperforming economy and the deluge of corruption charges against Mr. Chen and his family were bigger factors. While voters were looking for stronger economic ties with China, there is no evidence that the election results were a mandate for appeasement of the mainland, much less for any moves toward reunification.

So it’s important that Mr. Ma be able to show voters he’s not simply making an endless series of one‐​sided concessions. Yet Beijing hasn’t been willing to play ball so far. Despite repeated calls in Taiwan for Beijing to remove the more than 1,200 missiles aimed at the island, Chinese leaders show no inclination to reduce that number. Nor has Beijing shown any willingness to allow Taiwan to become a member of the World Health Organization or other international bodies. That unresponsiveness plays into the hands of DPP hardliners who argue Taiwan has gained little from Mr. Ma’s conciliatory efforts.

True, there have been encouraging steps toward economic collaboration and political dialogue. Within weeks of the new administration taking office, direct air links were established between Taiwan and the mainland, eliminating the need to route all travel through third‐​party hubs. Mainland tourists are now visiting Taiwan. And “unofficial“cross-Strait talks between Taiwan’s Straits Exchange Foundation and the mainland’s Association for Relations Across the Taiwan Strait (ARATS) have resumed, after being suspended for more than eight years.

However, not all Taiwanese are on board. In an especially ugly incident on October 21, ARATS vice president Zhang Mingqing was pushed to the ground during a scuffle with DPP demonstrators in the southern city of Tainan. An angry Mr. Zhang then cut short his trip to Taiwan and returned to Beijing. A few days after Mr. Zhang departed, several hundred thousand demonstrators poured into the streets of Taipei to denounce the KMT government’s rapprochement with China.

The key to maintaining the “Ma thaw” will be showing that Mr. Ma’s approach can succeed in extracting important concessions from Beijing — particularly given the ongoing evolution in public opinion regarding the mainland. Public opinion surveys in Taiwan taken since the election confirm the public’s hostility to reunification with China. In an October survey published by the Global Views Survey Research Center, 67.5% of respondents disagreed with the proposition that Taiwan and the mainland should eventually unify. Only 19.5% favored that position.

Conversely, 50.6% said Taiwan should ultimately become a new, officially independent country, and only 34.1% disagreed with that course.

Opposition to reunification and support for independence were both significantly higher than they were in a similar 2006 poll.

Mr. Ma’s own popularity has plummeted, an ominous signal for hopes for a lasting reduction in cross‐​Strait tensions. Although he won the election with nearly 60% of the vote, his current approval rating is only 29%.

The continuing deterioration of Taiwan’s economy, reflecting the global slowdown, appears to be the dominant reason, but there is also a growing sense that he has been too “soft” toward Beijing.

If Beijing does not make meaningful concessions soon, Chinese leaders may find themselves facing a new DPP government following the 2012 elections. The re‐​emergence of the KMT as the majority party in Taiwan may have postponed a showdown between Taipei and Beijing over the island’s political status, but it has not eliminated that danger in the long run.