The Department of Homeland Security has a new report called “Rightwing Extremism: Current Economic and Political Environment Fueling Resurgence in Radicalization and Recruitment.” It contains the following definition of right-wing extremism:
Rightwing extremism in the United States can be broadly divided into those groups, movements, and adherents that are primarily hate-oriented (based on hatred of particular religious, racial or ethnic groups), and those that are mainly antigovernment, rejecting federal authority in favor of state or local authority, or rejecting government authority entirely. It may include groups and individuals that are dedicated to a single issue, such as opposition to abortion or immigration.
You can read the whole article here. Source: The Liberty Papers