Democratic presidential candidate Sen. Hillary Clinton, D-New York, also appeared to question the university's decision Monday.Watch Sen. Clinton call for intense diplomacy with Iran »
"If I were the president of a university, I would not have invited him, but I did not express an opinion about the decision made by Columbia," Clinton said. "Obviously I was very much against his desire to go to ground zero. I thought that was absolutely out of bounds and unacceptable and thankfully it was not permitted."
One of Clinton's chief rivals for the Democratic nomination, Sen. Barack Obama of Illinois, also said he would not have invited Ahmadinejad to Columbia but stood his ground Monday on his controversial remarks earlier this year that he would meet with him.