Legislators need to be bound to the same term limits as the President. Two terms and you're finished for life. No exceptions, no difference for congressmen or senators. Simple to understand and simple to implement.
Why is this important?
The petition is designed to raise awareness that politicians can't have it both ways. Most of the senior members in both legislative branches have been in Congress for multiple terms - and are therefore (a large) part of the serious problems our country is facing. Ironically they offer themselves as solving the very problems they are both (Democrats and Republicans) responsible for creating.