We consider a dynamic process of coalition formation in which a principal bargains sequentially with a group of  agents. This problem is at the core of a variety of applications in economics and politics, including a lobbyist seeking to pass a bill, an entrepreneur setting up a start-up, or a firm seeking the approval of corrupt bureaucrats. We show that when the principal's willingness to pay is high, reallocating bargaining power from the principal to the agents generates delay and reduces agents' welfare. This occurs in spite of the lack of  informational asymmetries or discriminatory offers. When this collective action problem is severe enough, agents prefer to give up considerable bargaining power in favor of the principal.