Washington — A group of Democratic senators led by U.S. Army veteran Tammy Duckworth of Illinois unveiled a proposal on Wednesday to shield certain undocumented family members of U.S. troops from deportation, a move aimed at safeguarding a little-known immigration program the Trump administration is considering ending.

The bill introduced by Duckworth would codify into law a U.S. Citizenship and Immigration Services (USCIS) program known as "Parole in Place," which has been "under review" by the agency since the summer. The discretionary relief, which began under President George W. Bush, has helped undocumented family members of service members adjust their legal status without having to leave the U.S. and possibly being banned from entering the country for up to 10 years.

"Can you imagine being one of those Delta Force operators going in to kill the leader of ISIS and finding out just before you go on this operation that, by the way, the country that you defend is now going to deport your wife and leave your kids at home by themselves?" Duckworth told CBS News on Wednesday. "Not only is this inhumane and un-American — it is just stupid."

Senator Tammy Duckworth of Illinois, right, lost both her legs after the U.S. Army helicopter she was co-piloting was hit by a grenade launcher during a deployment in Iraq in late 2004. AP

The proposal introduced by Duckworth on Wednesday, dubbed the Military Family Parole in Place Act, is being co-sponsored by Senators Ed Markey, Catherine Cortez-Masto, Amy Klobuchar, Robert Menendez, Tim Kaine, Dick Durbin, Ron Wyden, Richard Blumenthal and Chris Coons.

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The Parole in Place program has been in place for more than a decade, with USCIS offering the discretionary relief to immigrant spouses, parents and children of active-duty soldiers, active reservists and honorably discharged veterans. But attorneys learned this summer that the Trump administration was considering to end the protection as part of the president's crackdown on legal and illegal immigration.

New: The Trump administration is reviewing whether to end a little-known program that helps undocumented family members of U.S. troops adjust their legal status. Teresa, 72, the mother of Army soldier Cesar Vargas, could be among the last beneficiaries:https://t.co/FrvBi1CehX — Camilo Montoya-Galvez (@camiloreports) August 22, 2019

A USCIS official said in August that the agency had not yet made a decision about terminating the program. Since immigration hawk Ken Cuccinelli was tapped to lead USCIS in early June, the agency has already ended two other parole programs: one for family members of aging Filipino veterans of World War II and the other for certain people in Haiti with family members who are U.S. citizens or permanent residents.

On Wednesday, a USCIS spokesperson said the relief for military families remains under review.

The U.S. government first started offering the Parole in Place relief after the wife of a U.S. soldier who was missing in action in Iraq was at risk of being deported in 2007, despite the service of her husband, whose skeletal remains were found the following year. After granting the wife Parole in Place, USCIS started to offer the protection under an official program, which enjoyed broad bipartisan support, including from Vice President Mike Pence, then a member of Congress.

The dilemma that the Parole in Place relief was designed to address stemmed from a Clinton-era law that made it much more difficult for undocumented people to adjust their status.

Under the Illegal Immigration Reform and Immigrant Responsibility Act of 1996, many unauthorized immigrants seeking green cards, through marriage to U.S. citizens or petitions filed by certain U.S. citizen family members, must leave the country, file an application overseas and likely face a three or 10-year bar from re-entering the U.S.

A "Parole in Place" document granted by U.S. Citizenship and Immigration Services (USCIS). Camilo Montoya-Galvez / CBS News

After getting the Parole in Place relief, military family members do not need to return to their home countries — and risk being banned from the U.S. for years — to adjust their status. By preventing potential separations of military families, the government hoped to improve troop readiness and morale.

But if the administration terminates the program, eligible undocumented family members of U.S. troops would effectively have no pathway to adjust their status without leaving the country.

Duckworth, who lost both her legs in Iraq in 2004 after a grenade struck the Army helicopter she was co-piloting, said the program's termination would undermine national security. She noted that Pentagon officials she spoke to were caught unaware by the administration's decision to review whether to end the program.

"It's bad for morale. It's the wrong thing to do. But it also completely undermines military readiness because now suddenly units overseas are going to find that members of their units suddenly are going to have to leave to come home to take care of family members," she said.

Along with codifying the existing program, Duckworth's proposal would require both the Pentagon and the Department of Veteran Affairs to sign off on USCIS denying a Parole in Place application. The Department of Homeland Security, which oversees USCIS, would also have to publish "detailed" justifications for denials online.

Duckworth said her bill aims to place the program on firmer grounds. "Let's put the power of the United States Senate and the power of legislation behind it and truly protect these men and women the way they are protecting us," she said.