Thompson said Romney "was one of the most adamant pro-choice advocates that I had ever seen."
COLUMBIA, South Carolina (CNN) – Two Republican presidential candidates slammed rival Mitt Romney's record on abortion Saturday, claiming Romney cannot be trusted on the issue because of his past support for abortion rights.
The attacks, some of the most pointed to date from his Republican opponents Fred Thompson and Mike Huckabee, come one week after Romney's campaign sent out a mailer in South Carolina calling him "the only major presidential candidate who supports the Republican party's pro-life platform: a constitutional amendment banning abortion nationwide."
The mail piece touts Romney as "the Governor who sided with life … every single time," referring specifically to legislation Romney supported while in office in Massachusetts.
Thompson, the former Tennessee senator who opposes an abortion amendment and says the issue should be decided by individual states, grinned when asked about the mail piece and said that before Romney decided to run for president, he "was one of the most adamant pro-choice advocates that I had ever seen."
"Governor Romney is saying a lot of things that I'm saying now," Thompson told CNN after a campaign stop in Summerville. "We're saying some of the same things. The only difference is that he was saying diametrically opposing things all his career."
Thompson, who picked up the endorsement of the National Right to Life Committee earlier this month, said that when voters consider Romney, they will have to decide "where he'll be tomorrow when the strong winds blow and when the strong pressure comes.'"
Huckabee also dismissed Romney's credentials on the issue and noted that he too supports a constitutional amendment banning abortions.
"When Mitt was out there on the other side of the issue and he was pro-abortion, I was marching the streets of Little Rock and passing a constitutional amendment in my state," Huckabee said while campaigning at a college football game in Columbia.
"Where Mitt comes up with that, I have no idea. You'll have to ask him how he can manufacture such ideas."
Romney spokesman Will Holley responded to the criticisms, saying that "Governor Romney is proudly pro-life and his record as Governor reflects that."
"Whether it was siding with life every single time an issue crossed his desk as Governor or his support for the Federal Marriage Amendment, Governor Romney has demonstrated his commitment to strengthening American families," Holley said.
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– CNN South Carolina Producer Peter Hamby