From Longman Dictionary of Contemporary Englishbe in/within somebody’s power (to do something)be in/within somebody’s power (to do something)CANif it is in someone’s power to do something, they have the authority or ability to do it I wish it was within my power to change the decision.do everything/all in your power The ambassador promised to do everything in his power to get the hostages released. → power
Examples from the Corpus
do everything/all in your power• I shall do everything in my power to help these poor creatures.• This might increase the temptation on the police to do all in their power to discourage complaints. 7.• Meanwhile the Cheetahs promise to do all in their power to ensure that Friday night's events are not repeated.• The Parish Council want to do everything in their power to prevent a serious accident.• Analysts say Milosevic is loathe to lose Belgrade and will do everything in his power to retain control of it.• And we will do everything in our power to help that customer get through her difficult financial times. 