This page on Willow computer games makes the same claim:
It should also be noted that Willow was originally intended to be a film adaptation of The Hobbit, but George Lucas could not procure the rights to the Tolkien franchises.
The Wikipedia page on Willow also used to say:
Lucas was originally going to do a film of JRR Tolkien's The Hobbit. But he was unable to get the rights.
But this has since been edited out because no source was provided.
- Did George Lucas once try to acquire the rights to The Lord of the Rings and/or The Hobbit,
or is this an unfounded rumour?