A supplier says producing the required quantity of a key component will take an additional month, but an important milestone is due in a week. What should the project manager do next?

The project manager should first ask the vendor if a minimally sufficient quantity of materials can be produced in time. This is the most immediate and practical step to mitigate the impact on the upcoming milestone. It explores a potential solution within the existing vendor relationship before escalating or seeking new suppliers. Performing market research or involving the legal department are more drastic, time-consuming actions that might be necessary later if this initial approach fails. Submitting a change request to extend the deadline without first exploring options to meet it is premature and reactive, rather than proactive problem-solving.