Critics and supporters of Arizona’s expanding private-prison system will have two hours Tuesday evening to weigh in on the state’s plan to add up to 2,000 medium-security beds. … Officials with Tennessee-based Corrections Corporation of America, the only bidder for the lucrative state prison contract, will be on hand with Arizona Department of Corrections administrators. CCA currently houses up to 1,000 medium-security inmates at its Red Rock Correctional Center in Eloy. That facility began housing state inmates in January 2014. That facility is expected to be the site of the first 1,000-bed expansion, according to CCA spokesman Steve Owen. He said there are more than 500 empty beds at Red Rock, and the company would renovate the facility to provide the additional beds. … Political proponents argue it is less costly for taxpayers to have private prison companies house inmates. Gov. Doug Ducey is among the proponents, and he has received tens of thousands of dollars in campaign contributions from private prison companies. However, there is no independent state study to support claims of the cost-effectiveness of prison privatization.