President Joe Biden on Wednesday renewed vows to secure a new ban on assault weapons in the United States as he turns up heat on lawmakers to pass legislation before his party loses control of Congress next month.

Lawmakers have shown little inclination to outlaw assault weapons since a ban on high-capacity firearms expired in 2004, but Biden is hoping to seize on outrage about the regularity of shootings to lead to greater pressure on them to change their mind.

“We did it before,” Biden said of the ban at a vigil for victims of gun violence at St. Mark’s Episcopal Church in Washington. “We did it, and guess what? It worked … We can do it again.”

The two-hour candlelight vigil, organized by the “Newtown Action Alliance,” memorialized the 10th anniversary of the Dec. 14, 2012, Sandy Hook elementary school shooting, when 20 first-grade students and six adults were murdered by a gunman with a semi-automatic rifle in Newtown, Connecticut.

“Guns are now the number one killer of children in America, and we are asked to be brave while hiding under our desks in our classrooms, while too many elected officials lack the courage to pass common-sense laws to save our lives,” said Jackie Hegarty, a student who survived the shooting, introducing Biden at the vigil.

Biden has made banning so-called assault weapons a rallying cry for his gun safety agenda after pushing a bipartisan law through Congress in June that includes provisions intended to help states keep guns out of the hands of those deemed to be a danger to themselves or others.

In November, Biden said “I’m going to try to get rid of assault weapons” and that he would “start counting the votes” on whether doing so was possible before the end of the current Congress on Jan. 3.

Pressed by reporters on Wednesday on where that pledge stands, White House spokesperson Karine Jean-Pierre said: “I don’t have any determination to share with you at this time.”

The House of Representatives remains in the hands of Democrats for just a few more weeks before Republicans become the majority party. Democrats will keep their majority in the Senate.

Gun control advocates are a major pressure group within Biden’s Democratic Party, while those opposed to new restrictions are a force in the Republican Party.