Sen. Lindsey Graham (R-SC) on Sunday defended his plan to introduce a 20-week abortion ban -- which may be unconstitutional -- in the Senate by arguing that the debate was "worthy of a great democracy."

With Graham facing more conservative challengers in the South Carolina Republican primary, the Washington Examiner reported last week that the senator intended to push a bill that would ban abortions after the fifth month of pregnancies as a companion to a similar bill that was passed in the House.

Fox News host Chris Wallace pointed out to Graham on Sunday that the Supreme Court had ruled that a woman's right to an abortion was protected until the fetus was viable at 24 weeks.

"At 20 weeks you feel pain," Graham argued. "We're trying to make the following argument to the Supreme Court, the state, the government has a legitimate interest to protect the child at the 20-week period of development because they can feel pain. And that's what a rational, humane society should do: protect a child that can feel pain from an abortion unless there's the life of the mother, rape or incest involved."

Wallace observed that many tea party conservatives had seen the abortion bill as a ploy to win the Republican primary after Graham had taken more moderate positions on immigration reform and Supreme Court justices.

"I've been a pro-life member of Congress since day one," Graham insisted. "I'm proud to lead this charge. This is a debate worthy of a great democracy. When do you become you? At 20 weeks of a pregnancy, what is the proper role of the government in protecting that child?"