Can anyone provide feedback on the following policy-based routing scenario...

Router-A (primary) and Router-B (secondary) share a comman ethernet segment. Router-A has an ATM connection to Router-C. Router-B has a Frame Relay connection to Router-C. HSRP is configured on Router-A and Router-B such that Router-A is primary. I want to policy route all HTTP (TCP port 80) over the Frame Relay link on Router-B as long is it is up and active. If it goes down all HTTP traffic should be routed over the ATM link on Router-A. I've configured basic policy routing on Router-A that sends all HTTP traffic to Router-B but problems arise when the Frame Relay goes down. Any suggesions on how to configure policy routing for this scenario?