The Roper Center has made available its entire collection of Primary exit polls. Primary exit polls datasets include standard demographic makeup of interviewee and questions pertinent to the issues of each state.
A list of Roper Members is available at https://ropercenter.cornell.edu/list-of-members/
The iPOLL Databank: Comprehensive resource for US public opinion; Contains over 650,000 questions & answers•1935-present -- 80 years of US national polls
There is no connection today between the non-profit Roper Center for Public Opinion Research at Cornell University and the for-profit Roper Poll owned by GfK Group. Public opinion pioneer Elmo Roper founded both organizations, but they are completely separate entities.