The National September 11 Memorial & Museum could get up to $20 million a year in federal money under a new proposal from three U.S. senators, who said they hoped to trim suggested museum admission fees that organizers have said could be $20.

New York Sens. Charles Schumer and Kirsten Gillibrand and Daniel Inouye of Hawaii announced the proposal Saturday, on the eve of the attacks’ 10th anniversary and the memorial’s opening. The Democratic senators said the money would ensure that the museum, run by a nonprofit group, was both financially viable and accessible to the millions of expected visitors each year.

Sept. 11 “was an attack on America, and supporting the site that memorializes the tragedy and heroism of that day is a national responsibility,” Schumer said in a release, saying he hoped federal help would “reduce the cost of admission so that no American who wishes to come to this hallowed ground is ever turned away.”

The proposed federal contribution would have to be matched with private money. Indeed, it represents about a third of the memorial and museum’s annual costs.

Still, the proposal would “provide needed resources for the memorial and museum to continue to serve as a symbol of the city and nation’s resilience and unity,” Gillibrand said in a statement.

The memorial plaza, which centers on waterfall-filled reflecting pools inscribed with the names of the nearly 3,000 people killed in the 2001 attacks, opens to victims’ families Sunday and the public Monday. Public admission is free but requires reserving a ticket.

The museum is set to open next year. While victims’ relatives will be admitted for free, memorial foundation President Joe Daniels told City Council members in June that members of the general public could be asked to pay about $20 if no other ways could be found to finance its upkeep.