A push led by Democrats to give more time for states to ratify the Equal Rights Amendment, or ERA, failed on Thursday.
The measure didn't win the support needed to clear a key 60-vote threshold, with the final tally being 51 to 47. Senate Majority Leader Chuck Schumer changed his vote to no in order to bring it back again in the near future.
"This issue is too important, and we are not giving up," Schumer said in brief remarks after the vote.
Almost all Republicans voted against the legislation, though Sen. Lisa Murkowski, R-Alaska, lobbied for it in floor remarks before the vote. "We've certainly made great strides as women since 1923, but there is a lot more that needs to be done," she said
The ERA, first introduced in Congress a century ago, would enshrine gender equality in the Constitution and states that rights "shall not be denied or abridged by the United States or by any state on account of sex."
Democrats renewed efforts to ratify the ERA following the Supreme Court's reversal of Roe v. Wade last summer, which ended the national right to abortion and prompted a wave of state-level bans on the procedure.
In recent weeks, a new legal battle over medication abortion has been thrust to the fore after a federal judge in Texas sought to suspend the government's decades-old approval of the widely used abortion pill mifepristone.
The Supreme Court has since paused that ruling as proceedings continue in lower courts.
"If you look at the terrible things happening to women's rights in this country, it's clear we must act," Schumer said in a floor speech on Thursday.
The ERA was passed with bipartisan support in 1972 but ultimately fell short of the three-fourths majority of states needed to ratify it before a deadline set by Congress.
The resolution voted on Thursday in the Senate would've removed the deadline for state ratification.
"There is no good reason -- none -- for this chamber, this Congress and this nation to bind itself to limitations set 50 years ago," Schumer argued ahead of the vote.
Three states in recent years voted to ratify the amendment -- Nevada in 2017, Illinois in 2018 and Virginia in 2020 -- and advocates argue that has propelled it to the state threshold needed for the resolution to be added to the Constitution.
However, the courts and Department of Justice have disagreed, citing the prior missed deadline from Congress that Thursday's vote would have addressed.
"States have met the threshold ratification, the only thing standing in our way is the arbitrary deadline set by Congress," Rep. Ayanna Pressley, D-Mass., told ABC News Senior Congressional Correspondent Rachel Scott last month.
Pressley and other members of the the ERA Caucus and the Democratic Women's Caucus on Thursday marched through the Capitol to the Senate for the vote.
The Biden White House has expressed support for the ERA, saying earlier this week that Congress should act quickly.
"In the United States of America, no one's rights should be denied on account of their sex," press secretary Karine Jean-Piere told reporters. "It is long past time to definitively enshrine the principle of gender equality in the Constitution."
ABC News' Gabe Ferris, Lalee Ibssa and Allison Pecorin contributed to this report.