President Barack Obama nominated former U.S. Sen. Hagel, R-Neb., as Secretary of Defense Leon Panetta's replacement. Hagel has drawn criticism from Republicans who say they are concerned about his stance on Israel and Iran.
Sen. John Cornyn, R-Texas, wrote for CNN that Hagel is seen as too tough on Israel and too soft on Iran.
"Where I think people are going over the line is with ad hominem attacks -- questioning for example whether [Hagel is] an anti-Semite," Haass said in an appearance on ABC's "This Week." "I've known Chuck Hagel for more 20 years. For what it's worth, I think that's preposterous. I also don't think that has a place in the public space."
Haass said the only thing relevant is Hagel's ability to run the Pentagon and his policy views.
"And I think there is a space and there should be a space for the hearings, and more broadly, to ask Chuck Hagel what is he prepared to do about Iran, what does he think the right mix, say, is of sanctions or possible use of military force? What should we be doing about cutting the Pentagon budget or ... about nuclear issues? All totally legitimate."
Earlier in the roundtable interview, Sen. Bob Corker, R-Tenn., said he questions whether Hagel's temperament is suitable for the position of secretary of defense.
"I think another thing ... that's going to come up is just his overall temperament, and is he suited to run a department or a big agency or a big entity like the Pentagon," Corker said.