“The fact that Marco Rubio is willing to support these bills renders his opposition moot,” said Rebecca Kiessling, president of Save the 1, an advocacy group that opposes abortion in all cases. “It’s useless because he’s not willing to take a stand on it.”

Ms. Kiessling said that lawmakers who compromise on abortion legislation, despite their good intentions, neglect the suffering of unborn children conceived through violent means.

Dan Becker, president of the Personhood Alliance and the Georgia Right to Life group, concurred. While he applauded the case that Mr. Rubio makes against abortion, he argued that his actions do not live up to his words.

“We’re never going to be able to establish legal protection for all classes of human life while allowing and acknowledging exceptions within the movement,” Mr. Becker said, saying that many state groups opposed the 2013 bill, which Mr. Rubio sponsored with 39 other senators.