We conduct multi-person one-shot ultimatum games that reflect important aspects of collective bargaining. In all treatments a proposer has to divide a pie among herself and two groups of three recipients each. She cannot discriminate within, but across groups. A committee with representatives from one or both groups takes acceptance decisions. In a 2x2 design we vary (i) representation in the decision committee (one vs. both groups) and (ii) the decision rule (unanimity vs. majority voting). We find that (i) representation of a group in the committee is crucial for receiving a significant share, (ii), proposals are balanced only if both groups have veto power (iii) negotiations often fail if the decision environment gives insufficient guidance on what an appropriate proposal is and (iv) non-binding communication substantially reduces rejection rates and proposer shares.