Every year, on the anniversary of the decision by the highest court in the U.S. that gave women the legal right to choose when and whether they become mothers, activists on both sides of the abortion issue hold demonstrations across the nations to rally for their cause. But both abortion rights supporters and anti-abortion groups say this year is far from routine, with the anniversary of the Roe v. Wade decision by the Supreme Court falling on a rare day when Republican lawmakers in Congress, seemingly taking their cue from conservative-leaning state legislatures in recent years, plan to consider a measure to restrict access to an abortion.

President Barack Obama has vowed to veto any legislation that would limit women’s health care choices. House Republican leaders initially planned to vote on a bill Thursday placing strict limits on late-term abortions but instead opted to drop the legislation late Wednesday, citing the concerns of nearly two dozen GOP members that the bill would hurt the party’s chances of gaining the support of women and millennials in the coming presidential election cycle, the Washington Post reported. Lawmakers were instead expected to vote on a measure Thursday that prohibits federal funding for abortions -- a less controversial measure that the Republican-controlled House has passed previously.

The political sparring and demonstrations in Washington, D.C., over abortion rights are more than a symbolic moment for activists on either side of the emotional debate. “We’re not going to cede this to the other side,” said Angela Hooten, vice president of U.S. policy and advocacy programs for the Center for Reproductive Rights, a pro-abortion rights group. “Despite the fact that we have overwhelming support from the American public, the reality is that the chipping away of Roe means many women are losing its meaning.”

The Supreme Court decided Roe v. Wade on Jan. 22, 1973. The ruling permitted abortions and outlawed federal and state laws banning abortions altogether. House leaders had been poised to take aim at the landmark decision with the Pain-Capable Unborn Child Protection Act, known also as HR 36, which would ban all abortions after 20 weeks, when fetuses are generally considered viable. The bill’s sponsor is a Republican congressman from Arizona, which was among more than a dozen states to pass similar legislation limiting abortions in 2012 and 2013.

“I would say that there certainly has been a movement among the states, from the West to the East, particularly when we are talking about late-term abortions,” said Republican Arizona State Sen. Kimberly Yee, who, in 2012, sponsored an Arizona House bill to ban 20-week abortions that was signed into law by the state’s governor. The measure was struck down by the 9th U.S. Circuit Court of Appeals in 2013.

The science of when life begins lacks consensus among experts, but Yee said that shouldn’t discourage anti-abortion lawmakers from bringing legislation forward. "While it may fall on the anniversary of Roe v. Wade, it’s not just a symbolic gesture," Yee said of the House vote Thursday. "I commend them for their efforts. This is a good day for legislation like that."

For the first time in at least six years, anti-abortion activists have a Republican-controlled Congress to look to for federal restrictions on abortion. But state lawmakers have been pushing such measures for years. In 2013, 22 states passed 70 anti-abortion measures, including late-term bans, doctor and clinic regulations, and bans on insurance coverage of abortions, according to a recent analysis by the Guttmacher Institute, a think tank on global sexual and reproductive health. The institute said 2011 was the most active year for anti-abortion laws, when 92 measures were enacted.

Some of the measures enacted by states have restricted abortion access by putting onerous regulations on clinics and doctors who administer the procedure. In Texas, for example, regulations led to the closures of two-thirds of more than 40 abortion clinics, the National Journal reported. Just seven clinics remain open in a state with more than 5 million women of reproductive age, said Vicki Saporta, president and CEO of National Abortion Federation, a Washington, D.C.-based pro-abortion rights group.

“It’s become a hardship and truly an undue burden on women,” she said. “I think Texas clearly shows that the targeted regulations are an undue burden. They should be declared unconstitutional,” per the Roe decision.

Americans who have been polled on abortion rights seem to agree that Roe should not be turned back or eroded by measures at the state level. Around the 40th anniversary of Roe v. Wade, a Pew Research Center poll found more than 63 percent of Americans did not want to see the decision overturned, while 29 percent did. Last year, a Quinnipiac University Poll found people were almost evenly split on the degree to which abortion itself should be legal in all or most cases.

“It’s just common sense that you should protect human beings who can feel pain," said Barbara Holt, president of North Carolina Right to Life, an affiliate of the national anti-abortion group.

The White House promised Tuesday to veto HR 36 if the measure passed the House and Senate. “Women should be able to make their own choices about their bodies and their health care,” read a statement from the White House. Obama said later in his State of the Union address on Tuesday night: “We still may not agree on a woman’s right to choose, but surely we can agree it’s a good thing that teen pregnancies and abortions are nearing all-time lows and that every woman should have access to the health care she needs."

Jeanne Monahan-Mancini, president of March for Life Education and Defense Fund, has organized an annual anti-abortion rally on the Washington Mall since the Roe decision. The event draws thousands of anti-abortion activists from around the U.S. “It doesn’t become routine,” she said. “The march is unique every year. The crowds are enormous. There’s something about coming together about this cause. We believe in our hearts that it’s the human rights issue of today.”