I am not a lawyer. I wish you would not have looked. The question you need to ask is will their political views impede their ability to do the job requirements. If they do, you have a legitimate concern, if they do not, you would fall into the Civil Rights Act of 1964: "The Act requires the elimination of artificial, arbitrary, and unnecessary barriers to employment that operate invidiously to discriminate on the basis of race, and, if, as here, an employment practice that operates to exclude Negroes cannot be shown to be related to job performance, it is prohibited, notwithstanding the employer's lack of discriminatory intent."