WASHINGTON - The House of Representatives voted this evening to pass legislation to ban abortion after 20 weeks, except in what Democrats assailed as "narrow" cases of incest of a minor, rape, and health of the mother, prompting a partisan debate on the House floor as lawmakers grappled over the question of how soon a fetus is able to detect pain in the womb.

The bill, H.R. 1797 - Pain-Capable Unborn Child Protection Act, passed by a vote of 228-196. Six Republicans opposed the measure, while six Democrats crossed the aisle to support it.

Republicans contend that a fetus is capable of detecting pain well before the current cut-off for abortions, at 24 weeks.

"These aren't just fetuses, science now tells us that they can feel pain. These babies are just like the ones we see in Neonatal Intensive Care Units in hospitals in our area struggling for life, needing love," Rep. Joe Barton, R-Texas, said in support of the bill. "This law will protect children."

"As a republic founded on the notion of the inherent right to life of every human being, we have an abiding responsibility to ensure that the innocent and most vulnerable are adequately protected from the gravest and most appalling of injustices, especially murder," Rep Mike Kelly, R-Pa., added. "That is what today's legislation seeks to accomplish and I am proud to grant it my complete support."

Democrats, on the other hand, called the legislation an assault on women's reproductive rights and an attempt to override the Supreme Court's 1973 ruling in Roe. v. Wade.

"It is unconstitutional, and it is dangerous to the health and safety of American women," Rep. Zoe Lofgren, D-Calif., said. "It's a direct challenge to Roe v. Wade when the Court held that prior to viability, abortions may be banned only if there are meaningful exceptions to protect a woman's life and health."

"Republicans have repeatedly demonstrated a lack of understanding about basic women's healthcare, and this bill is just one more example of their continuing attack on women's rights," Rep. Dina Titus, D-Nev., added during debate on the bill. "It is a step backward for women's health."

Although the bill passed, its path to the floor was rocky at best. Last week during a mark-up in the Judiciary committee, Rep. Trent Franks, the lead sponsor of the legislation, said that "the incidence of rape resulting in pregnancy are very low." Franks later said that what he meant was that "pregnancies from rape that result in abortion after the sixth month are very rare."

Still, House Republican leadership decided that Franks would not manage debate on his legislation, and tasked Rep. Marsha Blackburn, a former member of the Judiciary committee, to oversee the GOP's floor debate.

Today, Franks called the bill "very truly and simply a deeply sincere effort" to protect "both mothers and their pain-capable unborn babies."

"Passage of today's landmark bill marks the first time in history, in either chamber of the U.S. Congress, that affirmative protection has been extended to unborn children," Franks, R-Ariz. said after the bill passed. "It is my prayer that today also marks a day when America finally opens her eyes to the humanity of these little victims and the inhumanity of what is being done to them."

The bill was also tweaked after the committee markup to allow exceptions for rape and incest of a minor. Those changes led some of the most conservative Republicans to abandon support for the bill.

"As a medical doctor, I believe it is my duty to protect children at all stages of life," Rep. Paul Broun, a Senate hopeful who removed himself as a cosponsor of the legislation after the changes were added to the bill, said in opposition to the legislation. "I am extremely disappointed that House Republican leadership chose to include language to subject some unborn children to needless pain and suffering. I will not support legislation that harms innocent children, and I will continue in my efforts to protect all unborn children by making abortion illegal at all stages of pregnancy."

The legislation stands no chance to pass the Democratic-controlled Senate, and the White House had vowed that the president would veto the bill had it reached his desk.

"Women should be able to make their own choices about their bodies and their health care, and Government should not inject itself into decisions best made between a woman and her doctor," read a statement of administration policy Monday. "The Administration is committed to the protection of women's health and reproductive freedom and to supporting women and families in the choices they make."

The six Democrats supporting this legislation are Reps. Henry Cuellar (Texas), Dan Lipinski (Illinois), Jim Matheson (Utah), Mike McIntyre (North Carolina), Collin Peterson (Minnesota) and Nick Rahall (West Virginia).

The six Republicans opposing the bill are Reps. Paul Broun (Georgia), Charles Dent (Pennsylvania), Rodney Frelinghuysen (New Jersey), Richard Hanna (New York), Jon Runyan (New Jersey) and Rob Woodall (Georgia).