Ryan was scheduled to host a town hall meeting on Wednesday near Green Bay, a part of the state that tends to lean Republican but that voted for President Barack Obama in 2008.
Romney is making a stronger play for Wisconsin since selecting Ryan, a Janesville native, as his running mate. Polls before the pick showed Obama with a lead but the most recent ones done in mid-August show the race is nearly even.
Ryan's visit is sandwiched in between two by Democratic Vice President Joe Biden. He was also in Green Bay last week and planned to host a rally at the University of Wisconsin-Eau Claire on Thursday.