Poll: Cruz leads Democratic opponent by 5 points
Former Ryan aide announces congressional bid
"I want to take my problem-solving skills to Congress. I think they need problem solvers, doers ... not talkers," Steil reportedly said.
No viable Republican candidate had entered the race before Ryan announced his retirement earlier this month. The primary is scheduled for Aug. 14.
Steil, who is from Ryan's hometown of Janesville, sits on the Board of Regents for the University of Wisconsin, the AP reported. He served as a legislative aide and economic advisor to Ryan in the early 2000s.
Meanwhile, local school board member Cathy Meyers will face off against iron worker Randy Bryce, nicknamed "Iron Stache," in the Democratic primary in Wisconsin's 1st District.
Ryan announced earlier this month that he would retire from Congress after his current term ends.
--Updated at 10:05 a.m.