Ernst repeated Clinton's comment in an interview on CNN's "State of the Union" on Sunday, saying Clinton's gender mattered less to Iowans than her record on women's issues.
"I would say Hillary, it's not enough to be a woman. You have to care about women's issues," Ernst said, listing strong economy, "great educational system" and strong national defense as women's issues in Iowa.
"You have to be a leader with a vision, and you have to show Iowans that you want it ... and not just a woman," Ernst said on CNN.
The first-term Republican senator hosted the inaugural "Roast and Ride" event in Boone, Iowa, on Saturday, where declared and likely GOP presidential candidates delivered speeches before potential voters.
On ABC's "This Week" on Sunday, Ernst said a "Reaganesque" candidate would win the Iowa caucuses.
"We have to have somebody that will express conservative views, of course, and I'm looking for somebody that is very Reaganesque, someone that can reach all aspects of our voting population here in America, all areas, not just a select few people," Ernst said.