Labeling Democratic presidential front-runner Hillary Clinton as "stupid" or "incompetent" will backfire on Republicans, warned female GOP congressional leaders.

Five Republican women in the U.S. House of Representatives gathered in Washington, D.C., on Tuesday for the first a brunch co-hosted by National Review, Google, and Empowered Women. During a panel discussion, the women were asked what the current field of GOP presidential candidates can do to appeal to female voters and compete with the former secretary of state.

"Women and men believe that Hillary Rodham Clinton is strong and intelligent," Rep. Ann Wagner, R-Mo., said. "[Clinton] may have issues that stand out like being a liar or untrustworthy, but I will tell you that we will fail and these men will fail if they try and package her as someone who is stupid and doesn't know her job."

The group of women said Clinton's female rival, Carly Fiorina, has been "very effective" in going after Clinton in a way that "doesn't turn off women," but said the male GOP contenders should heed the advice of their party's female leaders.

"They need us at the table to remind them of the words to use and the words not to use," Wagner said. "I think it's going to be very important for us to get out and bracket it the right way."