Ride herd on somebody/something
Definition 1 of 3
Pro Tip 1/3Active Supervision
Implies actively overseeing someone's actions, not just passively observing. 
Our manager has to ride herd on the new hires to ensure they follow procedures.
Pro Tip 2/3Responsibility
Suggests a person has been given the responsibility to control or guide. 
As the oldest cousin, I often have to ride herd on my younger cousins at reunions.
Pro Tip 3/3Colloquial Expression
It's a casual expression, not typically used in formal writing or speech. 
In meetings, I'm informal and say I'll ride herd on the project's progress.