I submitted my resume in response to a job posting on my college's jobs portal. Within a few days I was contacted via email by the office coordinator for the senator and was asked to come in a few days later for an interview. The interview was with the three office members besides the senator himself. They were really friendly and started off with a few joking remarks that made me feel comfortable and at ease. They took turns asking me basic questions on why I was motivated/qualified for the position, what my future plans were, etc. It only took about 20 minutes and I felt it went really well, there definitely weren't any "gotcha" type questions. This was verified when I received a call later in the afternoon offering me the position which I accepted on the spot. This was for an unpaid legislative internship in a senator's office. The one thing I would say is that having worked in the senate office for a few months now the types of people and general atmosphere very greatly from office to office so although similar I wouldn't expect the process to be exactly the same for internships in every office.