strengthen (one's) hand
To give someone the ability to do something better, more forcefully, or more effectively. The law aims to strengthen federal officers' hands when making arrests on suspicion of illegal immigration. The scandal is yet another issue that will strengthen her opponent's hand in the run up to the election.
strengthen the hand of (someone)
To give someone the ability to do something better, more forcefully, or more effectively. The law aims to strengthen the hands of federal officers when making arrests on suspicion of illegal immigration. The scandal is yet another issue that will strengthen the hand of her opponent in the run up to the election.