Kolarek has been designated for assignment, Marc Topkin of the Tampa Bay Times reports.
The left-hander was expected to be added to the big-league roster after a strong Triple-A Durham campaign, but the Rays have instead decided to remove him from the 40-man roster. Assuming he clears waivers, Kolarek could remain with the organization for now, but this move suggests he might need to move to a different team to get another shot at the big leagues.