Recently my manager has started looking for candidates for our team. One candidate in particular he was very bias towards because he worked with him in the past and despite not having a lot of experience, he was really good friends with him -- he introduced the whole team and invited him to our daily stand up (something not customary for our past candidates) and he even sat in some of the technical interviews which I feel may have caused some of the interviewers to be a little more lax than usual.
If he was a really strong candidate, I don't think there would be an issue but I know at least one interviewer (one of the more senior engineers on the team) already has said he doesn't feel he's very strong especially for the role asked and it looks like the candidate may be going through.
How should I, or any of the interviewers bring this up to our manager's attention?