The Trump administration may have broken a federal law when it lobbied countries to join its effort to attack reproductive rights around the world, four Democratic senators said Wednesday.

Sens. Dianne Feinstein (D-Calif.), Patty Murray (D-Wash.), Robert Menendez (D-N.J.) and Jeanne Shaheen (D-N.H.) wrote to administration officials decrying a letter circulated over the summer by Secretary of State Mike Pompeo and Health Secretary Alexander Azar, which pressured more than 70 countries to sign a joint statement opposing "harmful" sexual and reproductive health policies.

"The letter may violate the Siljander Amendment, which prohibits use of foreign assistance in lobbying 'for or against abortion.'"

—Sens. Feinstein, Murray, Menendez, and Shaheen

"The letter may violate the Siljander Amendment, which prohibits use of foreign assistance in lobbying 'for or against abortion,'" the senators wrote.

Furthermore, the lawmakers said they were "alarmed that your opposition to abortion care—as stated in the letter—harms women and families, as well as endangers millions of women and girls."

In the letter sent to the countries ahead of a meeting on universal health coverage in September, the U.S. called on officials to sign on to a document that would be presented at the summit. The statement expressed opposition to "a new international right to abortion" and "international policies that weaken the family" including those promoting sexual and reproductive health and rights.

In addition to possibly breaking federal law, the senators wrote Wednesday, the Trump administration had advocated "to deny resources and education that could help millions of women and girls around the world."

The administration was only able to convince 18 countries to sign the agreement in September, including Saudi Arabia, Russia, and Bahrain, while longtime U.S. allies including the U.K. and France supported an opposing statement affirming that "sexual reproductive health and rights is an integral part of universal health coverage."

In addition to the letter the U.S. sent to dozens of countries, the administration refused to agree to a U.N. resolution seeking to end the use of rape as a weapon of war in April, demanding that references to "sexual and reproductive health" be removed first.