Team member at work has a bad stutter and has an upcoming speaking role during a big conference call with our client. Should I check with them to see if they want me to find someone else to do it? I don't want to be offensive by asking.

Team member at work has a bad stutter and has an upcoming speaking role during a big conference call with our client. Should I check with them to see if they want me to find someone else to do it? I don't want to be offensive by asking. I think the title says it all.