(CNN) - Former GOP presidential candidate Rick Santorum offered no insight into his own political future in a Friday CNN interview, but did offer his thoughts as to why the Republican nominee lost to President Barack Obama on Tuesday.
"What Mitt Romney, in my opinion, didn't do was go out and vigorously defend the beliefs that he said he espoused and didn't go on the offense," Santorum said in an interview to air Friday on CNN's "Piers Morgan Tonight." "And when you're playing defense, which is what I believe the campaign was doing and Republicans were doing generally throughout the course of this campaign you're not going to win.
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"He didn't make it about those two fundamentally different visions for America," he said of Obama's re-election campaign, "and I don't think we did a very good job either as Republicans pointing out those fundamental differences and what type of freedom we're talking about."
Santorum ended his White House bid in April as his chances for the party's nomination dwindled. Among what was once a wide field of Republicans, he came closest to defeating Romney for the nomination.
The interview with CNN's Piers Morgan is to air at 9 p.m. ET on Friday.
Also in the interview, Santorum discussed the resignation of CIA Director David Petraeus after he acknowledged an extra-marital affair. Santorum said the affair was "very, very disturbing and shows incredibly poor judgment."
"Obviously an extramarital affair that particularly is one that is not known by your spouse or by others is one that can lead you to a position to be compromised, blackmailed and a whole host of other things," the former U.S. Senator from Pennsylvania said. "I mean this is a man who has an incredible about of knowledge and secrets and information that we don't want others to find out about, and if someone who would like to do ill to the United States would find that out or maybe even be involved in the planning of this extramarital affair - you don't know.
"The point is this is not something, this is not a vulnerability that you want your head intelligence person to be engaged in and can not be engaged in such things," Santorum continued.
Santorum spoke hours after the top Republican on Capitol Hill and Obama delivered separate public remarks on the approaching so-called "fiscal cliff," a collection of spending cuts and tax increases scheduled to take effect in the new year absent congressional action to cut the federal deficit. Santorum said it is the responsibility of both parties in Washington "to do business" and find a solution.
"We have to deal with this situation - we can not let taxes increase, we can't see these kinds of really damaging defense cuts in such a precipitous amount in a very short period of time," Santorum said. "No, there has to be some sort of agreement worked out, but I don't think Republicans, particularly House Republicans, should be in a position that they're going to just do whatever the president wants."
And he stayed mum on whether or not he would make a second bid for the White House in 2016.
"I don't intend to do anything right now other than spend the little time working to make sure that we don't walk away from the very principles that made our country great," Santorum said, citing projects including his political committee.