HARRISBURG — A key Senate committee on Monday approved a controversial bill that critics say would roll back abortion rights in Pennsylvania.

The bill, championed by Republicans who control the Senate, would ban abortions after 20 weeks of pregnancy except in medical emergencies, instead of the 24 weeks allowed under current law.

The Judiciary Committee passed it along partisan lines just days after it was introduced — and without first holding a hearing or seeking input from medical organizations, a number of which have expressed concerns about its potential impact on decisions made between doctors and patients.

Though a nearly identical bill moved through the legislature last year before failing to win passage, this effort could have more momentum.

The measure now moves to the floor of the Senate, where it could come up for a final vote as early as this week, before heading to the GOP-controlled House.  And though Gov. Wolf, a Democrat, has vowed to veto the legislation, Republicans have larger majorities in both chambers this year and will likely receive support from conservative Democrats to attempt to override a vero.

Republicans have majorities in both chambers this year that are large enough to override his veto.

The bill would follow the lead of more than a dozen other states that have moved to put newer restrictions on abortions. Abortion opponents in 19 states have enacted laws that ban abortions at 20 weeks, even though viability is currently about 24 weeks measured from a woman's last menstrual period.

Pennsylvania's bill "is really pulling from trends we've seen across the country," said Elizabeth Nash, a policy analyst for the Guttmacher Institute, a reproductive health research center that supports abortion rights.

State health department data shows 31,818 abortions were performed in the commonwealth in 2015. Of those, 380 — or less than 1.2 percent — were performed after the 20th week of pregnancy and would be banned if the law passes.

Beyond the 20-week provision, the bill would also sharply curtail a procedure known as dilation and evacuation, often used in second-trimester abortions, according to medical experts. The bill itself refers to the procedure as "dismemberment abortion," although that is not a medically accepted or defined term.

At Monday's hearing, Sen. Stewart J. Greenleaf (R., Montgomery), the committee's chair, said the legislation was necessary given what he said was "significant" medical research showing that fetuses can be viable before 24 weeks. He did not offer any examples; medical experts say the age of viability has barely budged since 1973, despite improvements in technology.

He urged the U.S. Supreme Court to revisit the question of viability and the impact of medical advances on the ability of a fetus to survive outside the womb. Viability was a key component in the high court's landmark Roe v. Wade decision legalizing abortion.

The high court is not currently considering a case involving those issues, but Greenleaf said he believes that until that time, there should be legislative protections in place at the state level.

"The science has changed," he said in describing his support for the measure. "And we have children who are being aborted who are viable."

Opponents, all Democrats, called the legislation a thinly veiled effort to roll back constitutionally protected rights.

Sen. Lisa Boscola (D., Lehigh), the only woman on the committee, noted that abortions after the 20th week of pregnancy often occur because serious medical problems have been discovered.

"What this bill does is more a cookie-cutter approach when it comes to patient complications," said Boscola, adding: "These are heartbreaking decisions being made."

The U.S. Supreme Court's 1973 ruling in Roe v. Wade said that states may ban abortions, but only after the fetus can survive independently, and only if there is an exception to protect the woman's health.

Federal data shows that abortions have been falling for decades and reached a historic low in 2014, a trend that experts attribute to better use of contraception as well as laws that have reduced access to abortion. What's more, 95 percent of abortions are performed before 16 weeks, according to Guttmacher.

National Right to Life, the oldest, largest anti-abortion group in the United States, has been pushing for state laws that eliminate viability as the threshold for abortion bans — but based on the idea that the fetus can feel pain by 20 weeks after fertilization. Although that is a hotly debated question with limited scientific evidence, 16 states have tied their 20-week bans to fetal pain, said Ingrid Duran, the state legislative director for National Right to Life.

"We call the model law the 'pain-capable unborn child protection act,'" Duran said, adding that Pennsylvania's proposal is "not the perfect bill" because it doesn't talk about fetal pain.