In most states, there is no law against political activity retaliation. An employee could be disciplined or fired for leaving work to attend a rally or other political event, even if they are allowed to leave for lunch. However, employers who allow their employees to leave the premises for breaks would probably find it not worth the effort to clamp down on this type of political participation. While an employer can enforce its lunchtime period and penalize employees who are a minute late back to work, most companies realize that this is very bad for morale. Also, employees who are exempt from overtime have even more leeway with temporary absences from work. Realistically it is difficult for employers to prevent employees from using their lunch breaks to engage in political activity. Employees who do not have legal protection under anti-retaliation laws should be aware of the risk. The risk is higher if the political views you support conflict with the views of the company or your supervisors. It's always wise to not let outside activities interfere with your work during working hours. Even if your company doesn't strictly enforce the lunch hour, you should not take advantage of this by being absent for too long, regardless of the reason.