A stalking horse is someone whose role is to become the focal point for, or the initiator of, a debate or challenge. In reality, however, their leadership role may be an illusion. In practice they are working to promote a challenge or debate that will benefit a third party whose identity remains a secret.

The phenomenon occurs particularly in politics, where a junior politician acts as a stalking horse to promote the interests of a senior politician who cannot be seen to act in case it would damage him or her but nevertheless wants to provoke a debate or challenge to a party colleague. In some cases stalking horses are not working for a particular individual but may wish to provoke a response that leads others to join in. In politics, the truth about relationship between an individual stalking horse and a candidate may never be known, as both sides claim that that stalking horse acted without the agreement of anyone else.

In some cases, a single lead candidate, though themselves desiring to benefit from a crisis, may be described as a stalking horse. A classic example was Michael Heseltine, who challenged and brought about the defeat of Margaret Thatcher in the Conservative Party leadership. As with Heseltine, stalking horses rarely win the position of leader themselves, but leave the office open for someone else. Hence leading politicians seeking political power rarely take on the role of stalking horse, preferring some third party to trigger the staged crisis, they themselves then suggesting they are entering the debate or the election because it is occurring, not because they caused it to occur.

A classic example occurred in the Republic of Ireland in 1992, when former Fianna Fáil minister Sean Doherty, who had once been engulfed in a scandal over the revelation that as Minister for Justice he sanctioned the tapping of two journalists' telephones. At the time of the scandal in 1982 Doherty claimed that then party leader Charles Haughey played no part in the tapping of the telephones. In 1992 however he changed his story and insisted that Haughey had been an active participant. In the resulting furore, Haughey, who was taoiseach was forced to resign and was replaced by former Minister Albert Reynolds. Media critics regarded Doherty as a stalking horse for Reynolds though both men denied any involvement in what the media alleged was a "staged crisis", Doherty insisting that he acted alone in provoking the crisis, without having consulted Reynolds, much less acted for him.