House Speaker Paul D. Ryan (R-Wis.), with House Majority Leader Kevin McCarthy (R-Calif., center) and Republican Conference Chairwoman Cathy McMorris Rodgers (R-Wash., left), responds to a question during a press conference on Capitol Hill on Oct. 3, 2017. (Thew/Epa-Efe/Rex/Shutterstock)

The House on Tuesday approved a bill banning most abortions after 20 weeks of pregnancy, advancing a key GOP priority for the third time in the past four years — this time, with a supportive Republican in the White House.

The bill, known as the Pain-Capable Unborn Child Protection Act, is not expected to emerge from the Senate, where most Democrats and a handful of moderate Republicans can block its consideration. But antiabortion activists are calling President Trump's endorsement of the bill a significant advance for their movement.

The White House said in a statement released Monday that the administration "strongly supports" the legislation "and applauds the House of Representatives for continuing its efforts to secure critical pro-life protections."

[Trump’s budget proposal aims to cut all federal funds to Planned Parenthood]

The bill provides for abortions after 20 weeks gestation only when they are necessary to save the life of the mother or in cases of rape or incest. Under the bill, abortions performed during that period could be carried out "only in the manner which, in reasonable medical judgment, provides the best opportunity for the unborn child to survive" and would require a second physician trained in neonatal resuscitation to be present.

"It's past time for Congress to pass a nationwide law protecting unborn children from the unspeakable cruelty of late-term abortion," said Marjorie Dannenfelser, president of the Susan B. Anthony List.

Trump first supported a 20-week abortion ban in September 2016, during the final stretch of the presidential campaign when he was working to consolidate conservative support. Antiabortion activists argue the bill is justified by emerging scientific research indicating that a fetus can feel pain at 20 weeks, though the American College of Obstetricians and Gynecologists has not endorsed those findings.

[Donald Trump took 5 different positions on abortion in 3 days]

The vast majority of abortions are performed earlier in pregnancy, according to federal statistics, but activists have long focused attention on what they call "late term" abortions.

In a letter circulated to antiabortion activists by the Susan B. Anthony List, Trump pledged to sign a 20-week abortion bill into law if he became president, which he said "would end painful late-term abortions nationwide."

In that letter, Trump also promised to defund Planned Parenthood, nominate justices to the U.S. Supreme Court who are opposed to abortion, make the Hyde Amendment permanent law and "advance the rights of unborn children and their mothers when elected president."

Trump rarely discussed abortion on the campaign trail and did little to promote his stance on the 20-week abortion bill, with his campaign declining to even authenticate the September 2016 letter.

The House passed the bill 237 to 189. Two Republicans opposed the bill, and three Democrats supported it.

Similar bills passed a Republican-controlled House in 2013 and 2015 but did not emerge from the Senate. Democratic leaders did not bring the bill up for a vote in 2013, and when GOP leaders brought it up in 2015, it did not clear a key procedural vote.

Sen. Patty Murray (D-Wash.), the ranking Democrat on the Senate Health, Education, Labor, and Pensions Committee, called the bill a "waste of precious time" Tuesday.

"Let me be clear: This bill is as dead on arrival in the Senate," she said, "just like it was the last time Republicans tried to pander to their extreme base by playing this particular political game with women's health."

Abortion rights groups and Democratic lawmakers panned the legislation ahead of its passage, arguing it is based on faulty science and contains no exception if a pregnancy would threaten a mother's health. They also said the rape and incest exceptions are too narrow and that the bill is likely unconstitutional under existing Supreme Court rulings.

Ilyse Hogue, president of NARAL Pro-Choice America, characterized the bill as an attempt "to mollify an agitated base and avoid Donald Trump's ire at the lack of legislative action under Republican leadership."

"Women making these difficult decisions need medical professionals, not tone deaf legislation," she said in a statement.

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