House Speaker Nancy Pelosi and Senate Minority Leader Chuck Schumer on Monday sent a letter to President Trump urging him to support gun background check legislation that has already been passed by the House.

The two Democrats called on Trump to intervene personally to “stem the endless massacres of our fellow Americans by gunfire,” noting that 51 people were killed in mass shootings in August.

​”We have a responsibility to make our schools, shopping centers, houses of worship and other public places safer. The American people are crying out for their elected representatives to stop the epidemic of murder and mayhem that is shattering families and communities across the country,” says the letter sent as Congress returns after summer recess. “You are uniquely positioned to answer their call.​”​

Pelosi of California and Schumer of New York referred to comments made by Senate Majority Leader Mitch McConnell earlier this month that if Trump “took a position on a bill, so that we knew we would actually be making a law, and not just having serial votes, I’d be happy to put it on the floor.​”​

T​hey pointed to McConnell’s remarks as evidence that Republicans would be willing to follow the president’s lead and buck the powerful National Rifle Association to enact gun reform legislation.

​“We implore you to seize this moment when your leadership and influence over Republicans in Congress on the issue of guns is so critical,” ​Pelosi and Schumer say in the letter. “Please do not squander it by acceding to NRA-backed proposals or other weak ideas that will do nothing to stop the continuing, horrific spread of gun violence and may, in some cases, actually make our communities less safe.​”​

​Following the mass shootings in El Paso, Texas, and Dayton, Ohio, Trump signaled his support for strengthening gun background checks, but then wavered after speaking with NRA officials including CEO Wayne LaPierre.

The House passed the legislation in February but it has since been bottled up in the Senate by McConnell.