"People feel betrayed to think that Governor Romney -- who went out of his way to question the character, intellect and integrity of Donald Trump,... -- would be given the most significant cabinet post of all,..," Conway said Sunday on NBC's Meet The Press.
In a string of television interviews, Conway referred to Romney's attacks on Trump as "fraud" and "phony," and stressed the opposition to Romney's potential nomination by numerous Trump backers, reported USA today.
She told NBC, "I'm reflecting what the grassroots are saying."
Conway, however, also said the decision belongs to one person -- Trump -- and she would back his choice.
I did tell him privately. And I'll respect his decision. Point is the volume & intensity of grassroots resistance to Romney is breathtaking https://t.co/bknmfGZ13a— Kellyanne Conway (@KellyannePolls) 27 November 2016
"We're all for party unity," Conway said on ABC's This Week, but she added that "I don't think a cost of admission for party unity has to be the Secretary of State position."
Trump has interviewed Romney for the job. A prominent Trump campaign supporter, former New York City Mayor Rudy Giuliani, is also seeking the State Department post.
There are others in the mix, officials said, including John Kelly, a retired general, and Sen. Bob Corker.
There was also talk of retired general and former CIA Director David Petraeus, though he pleaded guilty in a case involving the sharing of classified information.