He says that will give voters a chance to weigh in. He didn't immediately name an interim successor. Topinka died last week. She had won a second term in November.
There have been conflicting ideas about her replacement.
Illinois Attorney General Lisa Madigan said Quinn can appoint someone until Jan. 12, when Gov.-elect Bruce Rauner takes office. After that, Rauner has the authority to name a full four-year replacement. However, Madigan also urged lawmakers to consider a special election in 2016 so voters could have a say.
That requires lawmakers to approve legislation.