stalking horse
Concise Oxford English Dictionary © 2008 Oxford University Press:
stalking horse
▶noun
- 1 a pretext used to conceal someone's real intentions.
■ a candidate for the leadership of a political party who stands only in order to provoke the election and thus allow a stronger candidate to come forward.
- 2 a screen in the shape of a horse behind which a hunter hides when stalking prey.
– origin C16: from the former practice of using a horse trained to allow a fowler to hide behind it.
'stalking horse' also found in these Oxford entries:

