Purchase requires assumption of current debt. Next Steps?

[Owen Burton]

I received a listing from a broker that requires the buyer to assume the property's existing loan.

If I determine a revised value that's ~$1M less than the listed principal amount (after adjusting vacancy etc. to 10% and expenses to 50%), what are the common next steps? Do I just ask the broker if the original lender is open to negotiating new terms? And if they're open to loan assumption financing?

Am I missing other obvious questions?