This paper studies the voting patterns of members of the U.S. Congress on financial regulation between 1991 and 2014. It uses the most comprehensive dataset assembled on campaign contributions from the financial sector and it is the first study on this subject taking a long-term perspective. This long-term approach allows me to address the problem of endogeneity in a new and more rigorous manner. I find that campaign contributions are the strongest driver of congressional voting. This variable increases the likelihood of voting in favour of deregulatory bills.