I'm applying for a summer internship at a big biology research lab in my city. This is such a fantastic opportunity and it would be such a tremendous help careerwise to get this experience. The application asks for 2 letters of recommendation from "individuals familiar with your academic performance." I've asked 4 professors and have gotten one yes, one no, and 2 haven't answered. The application states that the letters of recommendation must be attached to the application so I need to receive the letters of recommendation. Because of this, I think some of my professors are hesitant to write them.
With the deadline 2 weeks away I'm getting kind of desperate, would it be frowned upon if I get a former lab partner to write my second letter of recommendation seeing as they are an "individual familiar with [my] academic performance?" They have seen me in a lab setting and are familiar with my work ethic and technique. I'm not exactly best friends with them but I'm sure they would help me out in a pinch. Is there anyone else I can ask?