I need to talk to you about my group, and I do not want it to sound like a complaint about one person.

Go ahead.

Two of us have done most of the work for three weeks. When I ask for the part he promised, I get a reason, and then another reason.

Have you told him directly that you cannot do his work as well?

Twice. The second time he said it was my problem. Now the room is so bad that nobody wants to speak first.

Then being patient is not enough any more. What do you actually want?

Not punishment. I want the grade to reflect who did what, and I want one clear deadline for the missing part.

Then we will do it in writing, with his name on his section and yours on yours. If he misses it, it goes in his record, not in yours.

That works for me.