Romney, a former Massachusetts governor, was once "very pro-choice" and supported "strong positions for same-sex-relations," Huckabee said.
"He said on television that he would do more for the gay-lesbian agenda than Ted Kennedy. That's pretty bold. He said on television that he was not part of the Reagan Revolution, said that he was not part of that Reagan-Bush thing. That's on camera."
The former Arkansas governor, who acknowledged making the "political puberty" remark in a cable television interview, said Romney claims to be a gun rights supporter, but cannot be a "true Second Amendment" supporter because he supports an assault weapons ban.
"I think you can't just have a change of opinion on fundamental issues over and over and wait until you're running for president to do it," Huckabee said.
"To say you never thought about the origins of human life until you were nearly 60 years old, I find that hard to believe, even for someone who hadn't run for public office," he added.
Earlier Friday, Huckabee appealed to his Oklahoma supporters to spread the word that he is the most conservative candidate in the race and more attuned to their values.
After winning Iowa on Jan. 3, Huckabee has lost six straight nomination contests and his campaign is rapidly fading.
Romney - who won Michigan, Wyoming and Nevada, but lost New Hampshire, South Carolina and Florida to John McCain - expressed concern earlier this week that Huckabee will peel off enough conservatives to deprive him of victory over McCain in next week's Super Tuesday Republican nomination contests in 21 states.
"I think what will happen across the country is that conservatives will give a good thought to whether or not they want to hand the party's nomination over to Senator McCain. He has not been their champion over the last several years," Romney said the morning after losing Florida to McCain in a hard fought contest.
"I think there will be a movement within the Republican party to coalesce around a conservative candidate. Mike Huckabee, of course, might stay in, and that might be one of the reasons he does so is to try and split that conservative vote."
