ride herd over (someone or something)

To closely observe or monitor someone or something to supervise or maintain control. An allusion to a cowboy riding on his horse to keep a herd of cattle in order. We want the groups of students to work independently, but we should have a teacher riding herd over them to make sure each group stays focused. We're bringing in a consultant to ride herd over this project. We have to make sure it stays on schedule.