(CNN) - GOP vice presidential candidate and fitness fiend Paul Ryan poses lifting weights in pictures taken by TIME Magazine in December 2011 and published on Thursday.
In response to the photos, Ryan spokesman Michael Steel said, "Paul Ryan takes his health seriously. Clearly - judging by these silly pictures - he doesn't take himself too seriously."
But a Ryan aide told CNN later in the day that the publication of the photos was "poor judgment" and said they promised the photos would never be published.
Time Managing Editor Rick Stengel said in an interview on CNN's "The Situation Room" on Thursday that the magazine never promised that the pictures would not be published.
"We had discussions with them about using them back and forth and there was never an understanding that they would not be used," Stengel told CNN's Wolf Blitzer.
Responding to the Romney campaign reaction to the publication, Stengel said he is "sorry that they feel that way."
"He is in the news right now and we are in the news business, and this seemed like the most appropriate time to do those pictures," he said. "I kind of wonder if we had done them another time, you'd be asking me, 'Well why are you publishing those pictures of Paul Ryan? It seems sort of arbitrary and he's not in the news.' So you can't win either way."
- CNN Senior Congressional Correspondent Dana Bash contributed to this report