Only Vendors can declare their Intent to Bid (ITB), Buyers do not have the ability to do this on their behalf.
If a vendor has expressed interest externally but the ITB deadline has passed, you can extend the ITB deadline in order to permit the vendor to declare their Intent to Bid.
From the Details page, click on the Actions button and then Edit Schedule.
You can extend the Intent to Bid Due by selecting a new date via the date picker tool. This way the overall timeline for the project will remain the same.