Democrats are increasingly clamoring for President Barack Obama to use his authority to reinterpret a foreign aid law to allow for U.S. funds to be used to provide abortions to women who have been raped in conflict zones.

Led by Sen. Richard Blumenthal of Connecticut, 28 Democratic senators signed a letter to the president on Thursday urging him to relax the official interpretation of the Helms Amendment, a 1973 measure that forbids U.S. foreign assistance be used to pay for abortions “as a method of family planning.” In August, 81 Democratic House members raised a similar call in their own letter to Obama.

Democrats, women’s rights groups and faith-based humanitarian groups argue there is room to interpret the Helms Amendment as allowing abortions in the case of rape, incest or where the mother’s life is at risk.

“We write to express our deep concern for the reproductive health of women and girls who are kidnapped, enslaved, tortured, raped, and impregnated in conflict-affected zones worldwide,” the senators wrote this week. “Rape is increasingly used as a tool of warfare to destabilize communities, exert control over women and girls, and in some cases purposely impregnate them, as executed by Boko Haram in Nigeria and the Islamic State of Iraq and the Levant in Syria and Iraq.”

The senators called for Obama to issue a clarification to government agencies on the Helms Amendment to the Foreign Assistance Act of 1973 (PL 93-189) that would permit them to support safe abortion services in instances of rape, incest or to save the mother’s life.

House lawmakers in their letter said the current interpretation of the Helms Amendment was out of step with more recent congressional directives, which in fiscal 2013 and fiscal 2015 respectively extended federal coverage for abortion services to women in the armed services and the Peace Corps who had been raped or met the other two special exceptions.

“We encourage you to take this opportunity to ensure that the U.S. is correctly implementing the Helms Amendment,” the House members wrote. “The clarification we seek would require only the use of existing authority, and would not interfere with sovereign local laws.”

“For us, this is really a critical next step in really putting the pressure on the White House,” said Serra Sippel, president of the Center for Health and Gender Equity, which has been organizing support for a relaxation of the Helms Amendment.

Sippel noted that momentum has been building all year for a change, with mounting calls from House and Senate lawmakers, religious leaders and rape survivors.

“As advocates, we are optimistic that the White House will act. Time is running out [on the Obama administration] but we still feel like there is time for this president to act and do the right thing.”

National Security Council spokesman Peter Boogaard defended the president’s actions thus far, telling CQ the White House “will continue to work in consultation with Congress on the full spectrum of issues relating to this vitally important mission.”