It wasn’t Romney that has to clarify it, but Obama sure should. Read it again and find an answer for what is Obama’s explanation of “we did everything we could” after receiving the phone call;
Obama “Now with respect to Libya, as I indicated in the last debate, when we received that phone call, I immediately made sure that, number one, that we did everything we could to secure those Americans who were still in harm’s way;”
It would have looked like Romney was using Libya for political reasons.