Senate Democrats blocked House-passed legislation on Tuesday that would prohibit almost all abortions after the fifth month of pregnancy, a point when human infants can  feel pain and  survive if born prematurely.

The Pain-Capable Unborn Child Protection Act received the support of 54 senators, with 42 senators opposing it. Because of Senate rules, the bill needed 60 votes to advance. Joe Manchin of West Virginia, Joe Donnelly of Indiana, and Bob Casey of Pennsylvania were the only Democratic senators to support the bill. Mark Kirk of Illinois and Susan Collins of Maine were the only Republicans who opposed it.

Advocates of the legislation from the Susan B. Anthony list stood off the Senate floor during the vote with Danielle and Clayton Pickering of Iowa and their three-year old son Micah, who was born 20 weeks after conception, the point at which the national late-term abortion ban would take effect. Senator Joni Ernst, a Republican of Iowa, spoke about Micah on the Senate floor:

.@joniernst high-fives Micah Pickering (3), born @ 20 wks. Fam came from IA to lobby for Pain-Capable 20 wk limit pic.twitter.com/zykbCvu5WL

— Billy Valentine (@valentinebilly)
September 22, 2015

The national 20-week limit on abortion was introduced in Congress following the 2013 trial of Kermit Gosnell, an abortionist convicted of murder for killing babies after they had been born alive. Several prominent pro-choice Democrats, including Nancy Pelosi and Wendy Davis, have been unable to explain what the moral difference is between killing a born-alive infant at 23 weeks of gestation and aborting her.

Every Republican presidential candidate backs the legislation, but Hillary Clinton said on Sunday that she opposes any legal limits on abortion at any stage of pregnancy, falsely suggesting that late-term abortions are only performed because of "medical necessity." (The 20-week abortion ban includes an exception for when a physical health issue endangers the mother's life and when the pregnancy is the result of rape or incest.)

Several states and the District of Columbia have no laws prohibiting abortion throughout all nine months of pregnancy. One prominent late-term abortionist in Maryland admitted on camera that he will perform " purely elective" abortions through 28 weeks of pregnancy.

Several polls have shown that voters support banning abortions beyond the fifth month of pregnancy by a two-to-one margin. If enacted, the legislation would be the first federal law protecting human life at any stage of pregnancy since the 1973 Roe v. Wade decision.