In ROC it has to be the 2014 election for Taoyuan(桃園) Mayor
https://en.wikipedia.org/wiki/Taiwanese_local_elections,_2014#TaoyuanLike UK 1997 CON the ruling KMT was expected to do badly. But just how badly was a shock. The incumbent KMT Taoyuan Mayor John Wu(吳志揚) who is the son of former KMT Chairman and long time KMT Hakka political heavyweight Wu Po-hsiung (吳伯雄) was ahead in the polls by 15%-20% over DPP's Cheng Wen-tsan (鄭文燦). Wu was seen as a rising KMT superstar and that after he wins re-election in 2014 and completes his second term in 2018 he could be at least a Vice-President candidate for the KMT in 2020 or someone that would be Premier in a future KMT administration. Given his Hakka background and popularity in vote rich Taoyuan he was seen as someone that can consolidate the KMT strength in Northern Taiwan Province Hakkas. Wu's father and grandfather were both County Magistrates of Taoyuan and his family has deep roots there.
In the end Wu was defeated in a shock defeat by 3% (51-48). It was something on one, including the DPP high command, expected. To some extent the signs where there. In 2009 when Wu first won he also faced Cheng and lead in the polls 20%-30% but managed to only win by 6% (52-46). But that was written off as 2009 was seen as a slightly pro-DPP year. In 2014 it was clear that it was a very strong pro-DPP year and the assumption is that unlike 2009 DPP supporters would be enthusiastic to express their support to pollsters. In the end it was another pollster miss just like 2009.
After his Wu was put on the KMT party PR list for the 2016 Legislative elections on the assumption that he will challenge Cheng in 2018 in a re-match. He was elected as a MP which he had as a role back in 2004-2009. In the end he choose not to run in 2018 most likely on the calculation that Cheng is fairly popular and that while 2018 will have a slight KMT lean it is not enough for him to win. Not running in 2018 most likely means the end of Wu's political career. At best he runs in 2020 for MP but he will rise no higher then that.
