(CNN) Republican presidential candidate Rick Santorum once likened homosexuality to bestiality and now, about twelve years later, he is softening his tone.

Santorum, a deeply religious social conservative, says he "absolutely" regrets the comments, which he first made as a senator from Pennsylvania back in April 2003 in an interview with the Associated Press, as he discussed the then pending Supreme Court case over sodomy laws in Texas.

"I wish I had never said that ... It was a flippant comment that should not have come out of my mouth. But the substance of what I said -- which is what I referred to -- I stand by that ... I wish I had not said it in the flippant term that I did. And I know people were offended by it and I wish I hadn't said it," Santorum said Wednesday in an interview with MSNBC's Rachel Maddow.

Santorum has been recently showing a softer side on LGBT related issues. After then-Bruce Jenner's interview with Diane Sawyer in which Jenner spoke publicly about the transition from male to female.

"If he says he's a woman, then he's a woman," Santorum told BuzzFeed News in May, adding that it is his "responsibility as a human is to love and accept everybody."

And after Caitlyn Jenner's debut in June, Santorum suggested that while he does not agree with her decision, he respects it:

"My job as a human being is to treat everybody with dignity or respect — period, stop, full stop, no qualification to that," Santorum told CNN's Erin Burnett in June. "Do I have to agree with their positions on issues or how they see America? Of course not."

Photos: Rick Santorum's political career Photos: Rick Santorum's political career Former Sen. Rick Santorum of Pennsylvania speaks at the Point of Grace Church for the Iowa Faith and Freedom Coalition 2015 Spring Kickoff on April 25 in Waukee, Iowa. Hide Caption 1 of 15 Photos: Rick Santorum's political career Santorum speaks at the Point of Grace Church for the Iowa Faith and Freedom Coalition 2015 Spring Kickoff on April 25 in Waukee, Iowa. Hide Caption 2 of 15 Photos: Rick Santorum's political career Santorum speaks at the NRA-ILA Leadership Forum on April 10 at the NRA annual meeting in Nashville, Tennessee. Hide Caption 3 of 15 Photos: Rick Santorum's political career Santorum appears at the NRA-ILA Leadership Forum on April 10 at the NRA annual meeting in Nashville, Tennessee. Hide Caption 4 of 15 Photos: Rick Santorum's political career Santorum fields questions at the Iowa Ag Summit on March 7 in Des Moines, Iowa. Hide Caption 5 of 15 Photos: Rick Santorum's political career Santorum speaks at the Iowa Freedom Summit on January 24 in Des Moines, Iowa. Hide Caption 6 of 15 Photos: Rick Santorum's political career Santorum speaks at the Conservative Political Action Conference in National Harbor, Maryland, on March 15, 2013. Hide Caption 7 of 15 Photos: Rick Santorum's political career Santorum voices his opposition to the U.N. Convention on the Rights of Persons with Disabilities during a news conference with his wife, Karen Santorum, and three of their children on Capitol Hill on November 26, 2012. His daughter Isabella, being held by his wife, was born with a serious genetic disorder. Hide Caption 8 of 15 Photos: Rick Santorum's political career Santorum tries one of the local craft beers while having lunch at Simon's Specialty Cheese following a campaign stop in Appleton, Wisconsin, on April 2, 2012. Hide Caption 9 of 15 Photos: Rick Santorum's political career Santorum bowls at Sabre Lanes in Menasha, Wisconsin, following a campaign rally on April 2, 2012. Hide Caption 10 of 15 Photos: Rick Santorum's political career Santorum makes a grilled cheese sandwich during a campaign stop at Simons Specialty Cheese on April 2, 2012, in Appleton, Wisconsin. Hide Caption 11 of 15 Photos: Rick Santorum's political career Santorum tours a vintage train car with his daughter Sarah during a campaign stop at the National Railroad Museum on April 1, 2012, in Green Bay, Wisconsin. Hide Caption 12 of 15 Photos: Rick Santorum's political career Santorum tours a train engine during a campaign stop at the National Railroad Museum on April 1, 2012, in Green Bay, Wisconsin. Hide Caption 13 of 15 Photos: Rick Santorum's political career Santorum addresses supporters in Lafayette, Louisiana, after winning the Alabama and Mississippi primaries on March 13, 2012. Hide Caption 14 of 15 Photos: Rick Santorum's political career Santorum greets supporters during an election night rally at the Steubenville High School gymnasium in Steubenville, Ohio, on March 6, 2012. Hide Caption 15 of 15

In 2003 Santorum had a sharper tone when describing Lawrence vs. Texas, the case where the Supreme Court ruled against anti-sodomy laws.

"If the Supreme Court says that you have the right to consensual (gay) sex within your home, then you have the right to bigamy, you have the right to polygamy, you have the right to incest, you have the right to adultery. You have the right to anything," Santorum told the AP interview.

"In every society, the definition of marriage has not ever to my knowledge included homosexuality," Santorum continued. "That's not to pick on homosexuality. It's not, you know, man on child, man on dog, or whatever the case may be. It is one thing. And when you destroy that you have a dramatic impact on the quality ..." when he was interrupted by the AP reporter, who said "I'm sorry, I didn't think I was going to talk about 'man on dog' with a United States senator, it's sort of freaking me out."

"And that's sort of where we are in today's world, unfortunately," Santorum said.

Santorum's shift in tone could be reflective of a wider change in the national dialogue on LGBT issues.

After the landmark Supreme Court decision legalizing same-sex marriage in all 50 states, Santorum fiercely criticized the decision, but focused more on overruling the democratic process: "When did it become the law of the land that the Supreme Court has the final say on anything?" he said at the National Right to Life convention in New Orleans earlier this month. "They do not have the final say on anything. The American people have the final say on everything."