Proxies -- grant a one way relationship

I would like Users to be able to grant a Proxy relationship to another User so that the recipient will be voting for both parties.

The goal is to use taxonomy to categories Vote Topics (nodes) and for a User to extend/grant a proxy right to another User to vote for them on a topic, a combination of categories, or all topics.

I picture the proxy holder voting on topics normally via votingapi (Up/Down in my case), using Rules to record the event, and a cron process to cast any proxy votes.

I am hopeful there is an approach that will reduce the work. User Relationships look like a good starting point, but I would greatly appreciate any ideas or opinions.

Thanks, Jerry