on a short leash. Not given much opportunity to get into mischief.

Veteran White House correspondent Helen Thomas used this phrase in describing the tight rein which the Bush administration kept on their press secretary, Ari Fleischer: “He's a likable young man, but they keep him on a very short leash.” Given his propensity for overstatement and hyperbole, perhaps not short enough. Fleischer did not last too long in the role, but remains a Bush loyalist.

see also: end of one's tether; unleash cf dog collar