Person who does not hold an office trying to unseat an incumbent?

A person who does not hold an office and is attempting to unseat an incumbent is typically referred to as a challenger or an opposition candidate. This individual may leverage public dissatisfaction with the current officeholder, promote their own vision and policies, and engage in grassroots campaigning to gain support. They often face significant challenges, including fundraising and name recognition, but can capitalize on shifting public sentiment to garner votes. Their campaign strategies often highlight differences in experience, policy priorities, and community engagement compared to the incumbent.