Recent research suggests that bureaucratic responsiveness to political preferences may depend as much on organizational capacity as it does on incentive alignment, information recovery, and the strategic interaction of principal and agent. Better-resourced bureaucracies should be more able to comply with new political directions, irrespective of their willingness to do so. But because so much bureaucratic capacity is sunk into implementing the prior policy commitments of current and former principals, responding to new political signals will depend – much more specifically – on agents possessing adequate slack resources. This spare capacity should aid signal detection and program development; decrease hesitance at over-committing to new assignments in volatile environments; and provide resources for implementing changes whilst maintaining prior commitments. Using two-way fixed-effects regression and a novel dataset of 1,430 legislative requests of the UK executive, we confirm that possession of slack resources specifically significantly increases the likelihood of bureaucracies consenting to program changes requested by parliament. Agents with slack also commit to more precise timelines for implementation. And survival analysis further reveals that, once committed, bureaucracies with increasing slack complete their assignments more expeditiously.