After a tortured 40-year journey, the Equal Rights Amendment could hit the benchmark it needs to become enshrined in the U.S. Constitution next week — but opponents are saying say not so fast.

Lawmakers in Virginia are expected to vote as early as next week to ratify the ERA, the amendment that would outlaw sexual discrimination first proposed almost a century ago. Passed by Congress in 1972, it holds that "Equality of rights under the law shall not be denied or abridged by the United States or by any State on account of sex."

Virginia would be the 38th state to sign off on the amendment — the number needed to officially make it the 28th Amendment. But opponents of the measure — and the Department of Justice — say the window to ratify the amendment closed almost 40 years ago.

While the Constitution doesn't put a time limit on states ratifying an amendment — the 27th Amendment took more than 200 years to become a reality — Congress put a seven-year time limit on ratification of the ERA in the preamble to the amendment. It was later increased to a total of 10 years, but that timeclock expired in 1982.

Bills are pending in the House and the Senate that would rescind the time limit, but the Justice Department's Office of Legal Counsel said in an opinion issued earlier this week that Congress doesn't have that power.

"Because the 1972 ERA Resolution has lapsed, the only constitutional way for Congress to revive the ERA, should it seek to do so, would be for two-thirds of both Houses of Congress to propose the amendment anew for consideration by the States," the opinion said.

The National Archives and Records Administration, the agency that certifies ratification of amendments, said in a statement that it would follow the Justice Department's guidance "unless otherwise directed by a final court order."

Rep. Jackie Speier, D-Calif., tweeted earlier this week that she plans on pushing ahead with her bill to rescind the time limit because the "power to amend the Constitution lies with Congress and the States."

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"There can be no expiration date on equality, and we will stop at nothing less than an America free from the injustice of sex discrimination," she said in a statement to NBC News on Friday, adding that she expects "an expeditious ratification of the ERA."

Advocates of the amendment are prepared to continue their fight in court.

"At the end of the day, this is one memo from one administration," Kati Hornung, the campaign coordinator of the grassroots group VAratifyERA, said in an interview. "Civil rights is never too old."

In the meantime, Hornung said, "It's a beautiful moment where Virginia finally gets on the right side of history."

First written by suffragist Alice Paul and introduced to Congress in 1923, there were failed efforts by Democrats and Republicans to pass what became known as the Equal Rights Amendment every year until 1972, when it passed with bipartisan support and widespread support from the public.

The seven-year time limit for ratification included in the clause introducing the amendment was a mechanism first used to speed passage of the amendment doing away with prohibition. By 1977, 35 states had ratified the ERA — but opposition led by conservative activist Phyllis Schlafly stalled the momentum.

Schlafly warned that ratification of the amendment could lead to women being drafted into the military, same-sex bathrooms and an increase in abortions. "What I am defending is the real rights of women," Schlafly said at the time. "A woman should have the right to be in the home as a wife and mother."

Five states moved to rescind their ratification — which most legal experts maintain can't be done — and the amendment appeared dead. Then, in 2017, Nevada ratified the amendment, followed by Illinois a year later. Virginia appeared poised to follow suit last year, but the measure was blocked from a vote by the Republican-controlled House of Delegates.

The new Democratic majority has vowed to ratify the amendment this year, and the state Senate is expected to vote on it as soon as next week.

Meanwhile, the Republican attorneys general of three states — Alabama, Louisiana and South Dakota — filed suit in federal court last month to block the National Archives from signing off on the amendment. Alabama and Louisiana never ratified the amendment, and South Dakota is one of the states that tried to rescind its ratification.

"The ERA cannot be ratified because the congressional deadline for ratification has expired," the suit says.

Advocates like Hornung maintain the Constitution gives Congress wide leeway when it comes to amendments — including the ability to lift the deadline.

Martha Davis, a constitutional law professor at Northeastern University School of Law, said "There’s going to be litigation and more efforts to increase public pressure."

"There's still an opportunity for Congress to jump in, and for the courts to come in . . . There will be lots of back and forth for a while," she said. "Nobody thought this would be easy. It's been many decades and generations in the making, and there's excitement that it's moving forward."