Jennifer Steinhauer, © 2016 New York Times News Service

WASHINGTON — In the latest and perhaps decisive battle over the role of women in the military, Congress is embroiled in an increasingly intense debate over whether they should have to register for the draft when they turn 18.

On Tuesday, the Senate approved an expansive military policy bill that would for the first time require young women to register for the draft. The shift, while fiercely opposed by some conservative lawmakers and interest groups, had surprisingly broad support among Republican leaders and women in both parties.

The United States has not used the draft since 1973 during the Vietnam War. But the impact of such a shift, reflecting the evolving role of women in the armed services, would likely be profound.

Under the Senate bill passed on Tuesday, women turning 18 on or after Jan. 1, 2018, would be forced to register for Selective Service, as men must do now. Failure to register could result in the loss of various forms of federal aid, including Pell grants, a penalty that men already face. Because the policy would not apply to women who turned 18 before 2018, it would not affect current aid arrangements.

“The fact is,” said Sen. John McCain (R-Arizona), the chairman of the Armed Services Committee, “every single leader in this country, both men and women, members of the military leadership, believe that it’s fair since we opened up all aspects of the military to women that they would also be registering for Selective Services.”

The Supreme Court ruled in 1981 that women did not have to register for the draft, noting that they should not face the same requirements as men because they did not participate on the front lines of combat. But since Defense Secretary Ash Carter said in December that the Pentagon would open all combat jobs to women, military officials have told Congress that women should also sign up for the draft.

“It’s my personal view,” Gen. Robert B. Neller, the commandant of the Marine Corps, told the Senate Armed Services Committee in February, that with the complete lifting of the ban on women in combat roles, “every American who’s physically qualified should register for the draft.”

While most Republican senators — including Mitch McConnell of Kentucky, the majority leader, and the women on the Armed Services Committee — agree with the move, it has come under fierce attack from some of Congress’ most conservative members.

“The idea that we should forcibly conscript young girls in combat to my mind makes little sense at all,” Sen. Ted Cruz (R-Texas), the father of two young daughters, said on the Senate floor last week.

After voting against the bill on Tuesday, Cruz said in a prepared statement: “I could not in good conscience vote to draft our daughters into the military, sending them off to war and forcing them into combat.”

The debate will now ... pit the Senate against the House, where the policy change has support but was not included in that chamber’s version of the bill.

In April, Rep. Duncan Hunter (R-California) offered a provision related to women and the draft for the House version of the defense policy bill to highlight the issue, even though he opposes the idea — then voted against his own amendment. It passed with bipartisan support but was stripped from the final bill in a procedural move.

“If he didn’t do this in the committee and spur the national debate, who was going to do it?” Joe Kasper, Hunter’s chief of staff, said. “So, mission accomplished.”

Sen. Mike Lee (R-Utah) made a mild attempt to strip the language from the Senate bill on the floor after the Armed Services Committee overwhelmingly rejected a similar effort, but his amendment never received a vote.

The two bills will now be reconciled in a conference committee between the House and the Senate, where a contentious debate is expected.

“It may well be a topic of great controversy,” said Sen. Richard Blumenthal (D-Connecticut), who serves on the Armed Services Committee. “But it should not be.”

Military experts say that even if the efforts to compel women to enlist fail in Congress, the issue is not going away.

“I think the change is inevitable,” said Nora Bensahel, a military policy analyst at American University’s School of International Service, “whether in this debate or through the courts. It just seems that now that you have women allowed to serve in any position in the military, there is no logical basis to say women should not be drafted.”

Conservative groups, which threatened to target senators who voted for the policy bill, reacted with anger on Tuesday to the bill’s passage. “Allowing our daughters to be forced into combat if there is a draft is a clear example of Washington placing more value on liberal social engineering than military objectives and preparedness,” one such group, Heritage Action for America, said in a news release.

But supporters of the policy change say opponents are oversimplifying the issue. “What people don’t seem to understand is just because there is conscription, that does not mean that all women would serve in the infantry,” Sen. Deb Fischer (R-Nebraska) said. “There are many ways to serve our country in the event of a national emergency.”

The Senate is expected to hold its ground as conservative members defend the status quo. McCain, whose family has a long and storied history in the military and whose daughter-in-law is a captain in the Air Force Reserve, said to Cruz on the Senate floor: “I respect the senator from Texas’ view. Too bad that view is not shared by our military leadership, the ones who have had the experience in combat with women.”

To Learn More:

House Republicans Strip Female Draft Sign-Up Requirement from Defense Bill (by Richard Lardner, Associated Press)

U.S. Generals Urge Congress to Require Women to Register for Military Service (by Lolita C. Baldor, Associated Press)

Draft Registration Front and Center in Sex Discrimination Case (by David Wallechinsky, AllGov)