In a tweet, the Vermont senator flatly stated, “Abortion is a constitutional right.” He did not elaborate.
The statement prompted swift rebukes on Twitter.
"When human life begins, human rights begin," tweeted March for Life, the anti-abortion group. "No one has the right to kill an innocent human being, no matter how young or helpless that human being is."
The U.S. Constitution does not specifically address abortion. But abortion-rights activists argue the 14th Amendment to the Constitution, as cited by the Supreme Court in the 1973 Roe v. Wade decision, includes a "right to privacy" that allows women to decide whether to have an abortion.
Sanders' comments follow Alabama’s legislature passing a bill that would make performing an abortion a felony at any stage of pregnancy with almost no exceptions.
Other Democratic presidential candidates have made similar arguments, as they blast Alabama’s bill.
“This is an outrage and it's nothing short of an attack on women's basic human rights and civil rights and it's something that women of America are going to have to fight against with everything they've got,” New York Sen. Kirsten Gillibrand said Wednesday on MSNBC.
Former Vice President Joe Biden tweeted, "Republicans in AL, FL, GA, and OH are ushering in laws that clearly violate Roe v Wade and they should be declared unconstitutional. Roe v Wade is settled law and should not be overturned."
Campaigning in New Hampshire on Wednesday, California Sen. Kamala Harris said of the Alabama abortion law: “This will not stand.”
In Alabama and other conservative states, anti-abortion politicians and activists emboldened by the addition of conservative justices to the U.S. Supreme Court hope to ignite legal fights and eventually overturn the landmark Roe v. Wade decision, putting an end to the right to abortion.
Fox News’ Paul Steinhauser, Ben Florance and The Associated Press contributed to this report.