Hopes have been raised that the only direct bus service between Hull and Grimsby could be saved.
Stagecoach, which operates the X1 service, is ready to withdraw the route claiming the Humber Bridge tolls are too high.
But following a meeting with local MPs and bus operators, the Humber Bridge Board has agreed to review its tolls.
Board Chairman David Gemmell said he was "cautiously optimistic" that an agreement would be reached.
But he said any decision taken to vary the tolls for bus operators had to be based on sound commercial arguments.
Bus operators currently pay £10 each way for their vehicles to use the bridge, although from midnight on 23 April, that will increase to £10.90.
The new charges were approved by the Secretary of State for Transport earlier this month after a public inquiry.
More than six million vehicles cross the Humber Bridge every year, generating approximately £18m.
The Humber Bridge Board pays out £15m every year in repayments for the construction loan, which it is estimated will be paid off in 2032.