flip-flopper

基本解释

The great flip-flopper does not convince the conservative base.
這位大騎牆派竝不能說服保守派基層。
Exposed as an un-Christian flip-flopper and shorn of the momentum that came from seeming inevitability, she will see her voters melt away.
羅塞夫被揭露爲一個言行不一的非基督教徒，竝且喪失了必然獲勝的勢頭，她的選民將漸漸消失。
Apart from being dull and being Mormon, which still fans suspicions, the famous flip-flopper is also—with the exception of his fellow Mormon, Jon Huntsman—the least authentic conservative in the race.
除了沉悶無聊，以及仍然招來懷疑的摩門教徒身份外，這位著名的騎牆派可能也是這次競選中（除了另一位摩門教徒洪博培以外）最不正宗的保守派。

Although does that give Republicans an opportunity to paint another Democratic presidential candidate as a flip-flopper?
NPR: Analysis: Congress And The Cost Of Energy
Nobody wants to be labeled a flip-flopper, not even a member of the FOMC.
FORBES: Through the FOMC's Looking Glass: An Orgy of Transparency
Consciously or otherwise, they reinforce Labour's attack on him as Chameleon Dave, the flip-flopper who believes in nothing.
ECONOMIST: Bagehot