The election was seen as a litmus test for the governing Democratic Progressive Party and the incumbent President Chen Shui-bian in the wake of damaging scandals affecting their image.

It was also a test for the popularity of the leading opposition party Kuomintang, which Taipei mayor Ma Ying-jeou assumed the chairmanship of in August 2005.

In the months preceding the election the DPP was plagued by a rising unemployment rate and a series of scandals involving the Kaohsiung Mass Rapid Transit system, stock speculations by two deputy presidential secretaries-general,[3][4] and "stock market vultures" profiting from insider information.

Publicized scandals concerning several KMT candidates failed to cause similar damage, in part because the DPP had built a reputation on its desire for reform, had the most to lose by the taint of corruption.

[citation needed] DPP planned to discontinue the current 18% pension interest rate for civil servants also backfired on the party.

The pension reform plan had been put forward by the Chen administration as a way to stop a drain on the national treasury caused by paying a favored interest rate to long-term KMT officials who had worked relatively short stints in actual public government.

Prominent beneficiaries of the high interest rate included KMT honor chairman Lien Chan and current Taichung mayor Jason Hu.

However, he was disqualified one day after inauguration on 20 December 2005 due to a corruption conviction that led him to be purged from the KMT.

Chen Chu of DPP was elected mayor of Kaohsiung, defeating the Kuomintang's Huang Jun-ying.

Su had pledged to step down if the DPP lost either Taipei County or failed to win 10 of the 23 mayor/magistrate positions.

Presidential Office Secretary-General Yu Shyi-kun was elected in a three-way race against legislator Chai Trong-rong and Wong Chin-chu with 54.4% of the vote.

Ma had declined to accompany Lien on his visit to mainland China earlier in the year and, as chairman, has appointed fresh faces to a number of party posts.

The election is thus widely read as an expression of voter confidence in Ma's ability to achieve reform within his own party as well as in government.

It also faced a defection in Taipei County where Chou Hsi-wei left the PFP to gain the KMT nomination.