This is a common deferral tactic. Offering to provide information to aid their discussion with their boss can help avoid this.
Step 1: Validate their objection
"I understand."
Step 2: Label it
"It sounds like this decision involves your boss."
Step 3: Follow up with a secondary ask
"Could we set up a meeting with your boss? Or, can I provide some information that would help you discuss this with them?"