Washington (CNN) The Justice Department's Office of Legal Counsel is arguing that the deadline to ratify the Equal Rights Amendment has expired, a blow to supporters' push to enshrine the long-sought effort.

"We conclude that Congress had the constitutional authority to impose a deadline on the ratification of the ERA and, because that deadline has expired, the ERA Resolution is no longer pending before the States," the OLC said in an opinion released Wednesday.

The opinion, issued in response to a lawsuit filed by three conservative-leaning states , effectively prevents the archivist of the United States, who administers the ratification process, from verifying that the amendment is valid and part of the Constitution after the necessary number of states approve it. But his authority doesn't prevent states from acting on their own to ratify the amendment -- or preclude them from legally challenging the Justice Department's opinion in court.

"OLC's opinion doesn't directly affect the litigation, but unless it is overruled by the attorney general or the President, it likely will bind the archivist -- meaning that the only way a new ratification by a state like Virginia would likely be effective is if the courts say so," Stephen Vladeck, a CNN legal analyst and professor at the University of Texas School of Law, told CNN. "This opinion suggests that, from the Executive Branch's perspective, the matter is closed."

Supporters say the ERA would ban discrimination on the basis of sex and guarantee equality for women under the Constitution, while opponents argue that the ERA would allow more access to abortion and that many protections are already enshrined at the state level.

ERA proponents see Virginia as the next, and 38th, state to ratify the amendment, which would meet the three-fourths threshold necessary for an amendment to be added to the Constitution. Virginia's state legislature returned to session on Wednesday and its Democratic lawmakers, who control both chambers, have said passing the ERA is a priority

But the OLC says that because the necessary 38 state legislatures didn't ratify before the initial 1979 congressional deadline, "the Equal Rights Amendment has failed of adoption and is no longer pending before the States." In its opinion Wednesday, the OLC disagreed with its own 1977 opinion that concluded Congress could extend a ratification deadline on an amendment pending before the states.

"Accordingly, even if one or more state legislatures were to ratify the proposed amendment, it would not become part of the Constitution, and the Archivist could not certify its adoption," the opinion states.

The OLC also says that Congress cannot revive a proposed amendment after it has exceeded its deadline for ratification, suggesting instead that Congress restart the ratification process from scratch.

The ERA Coalition, which supports the amendment, said it "strongly disagrees with the OLC's opinion that the time limit cannot be removed" and intends to pursue it regardless.

"We call on Congress to redouble its efforts to remove the time limit and we call on all remaining 13 states to ratify the ERA following the lead of Nevada, Illinois and soon Virginia," the ERA Coalition said in a statement Wednesday. "This OLC opinion is not binding on Congress, the courts, or the states that have expressed their ongoing will to give women constitutional equality."

"We believe it is imperative that Speaker (Nancy) Pelosi move ahead quickly with the floor vote to remove the time limit on the ERA," Marianne Stack, a spokesperson for the ERA Coalition, said in a statement Wednesday provided to CNN.

Efforts to eliminate the deadline are working their way through Congress, as bills have been introduced in both the Democratic-controlled House and GOP-led Senate.

A decades-old deadline

When Congress passed the ERA in 1972, it sent the amendment to the states to ratify within a seven-year window. That deadline was later extended by three years to 1982, but by then, only 35 states had signed off on the ERA.

By March 1979, five states that ratified the ERA had rescinded their decision. Two other states recently ratified that hadn't already done so -- Nevada in 2017 and Illinois in 2018.

Advocates for the amendment have argued that the 1982 deadline is not binding and that rescinding a ratification has no legal validity. Opponents of the ERA say the deadline for ratification has expired and cite the five states that rescinded or withdrew their ratifications.

Last month, Alabama, South Dakota, and Louisiana filed a federal lawsuit against the archivist of the United States, David Ferriero, in an attempt to stop the ERA from being added to the Constitution.

The conservative-leaning states argued that Ferriero was "acting illegally" by continuing "to hold open the ratification process" and refusing to recognize some states' rescissions of the amendment. In response, the National Archives and Records Administration temporarily paused on taking any action and reached out to the Justice Department for guidance.

The Eagle Forum -- a group opposed to the ERA and founded by Phyllis Schlafly , a prominent anti-feminist and early leader of the social conservative movement -- said the OLC opinion helps invalidate ERA supporters' claims that "only one state is left to ratify the amendment by blatantly ignoring the ERA's 7-year ratification deadline."

"We are hopeful today's opinion will force ERA supporters to begin the ratification process anew and therefore ensure all Americans have the opportunity to decide if they would like it ratified," said Kirsten Hasler, the group's executive director, in a statement.

The ERA has been reintroduced in the US Congress every year since 1982, with Democratic Rep. Carolyn Maloney of New York spearheading the latest efforts to get it passed.

CORRECTION: This story has been updated to correctly reflect that five states had rescinded their decision to ratify by March 1979 and to clarify that 38 state legislatures hadn't ratified by the initial 1979 deadline set by Congress.