政治上，跛脚鸭又称“瘸鸭”，指一个因任期快满而失去政治影响力的公职人员。成为跛脚鸭的原因有：

由于其他人倾向不与跛脚鸭合作，跛脚鸭的政治影响力会较低。不过，由于跛脚鸭无需在下届选举为自己的工作负责，这会使他们有更大自由提出不受欢迎的政策和任命。例如在美国，总统在任期将满时会赶在新总统上任前推出所谓子夜法例（midnight regulations）和行政命令。

A lame duck, in politics, is an elected official whose successor has already been elected. The official is often seen as having less influence with other politicians due to their limited time left in office. Conversely, a lame duck is free to make decisions that exercise their standard powers with little fear of consequence, such as issuing executive orders or other controversial edicts. Lame duck politicians result from term limits, planned retirement, or electoral losses.