Proposers strategically formulate legislative bills before voting takes place. However, spatial voting models that estimate legislator’s ideological preferences do not explicitly consider this fact. In our model, proposers determine the ideology and valence of legislative bills to maximize their objective functions. Approaching to the median legislator ideology and increasing costly valence increases the passing probability, but usually decreases the proposer’s payoff. Using quantile utility proposer preferences, the model becomes tractable and estimable. In this way, we deal with the bill sample selection problem to estimate legislator’s preferences and also, the ideology of proposers, the proposed valence change, and the ideological stance of the statu quo in a common scale. Using Chilean Senate 2009 – 2011 roll call data, our results suggests that (1) political party affiliation significantly affects Senators’ ideology, (2) popular, young and male Senators are more extremist, and (3) proposers during Bachelet and Piñera’s terms have similar ideologies.