According to White House estimates, the 11 Obama-era rulings that President Trump reversed in his first few months in office will save $10 billion over the next 20 years, Bloomberg reports.

It’s all thanks to an obscure 1996 law that allows Congress to quickly repeal legislation with a simple majority, the report adds:

The window to invoke the Congressional Review Act is April 28 and the Trump administration is hopeful that several other measures will pass both houses of Congress and reach the president’s desk before that date, Marc Short, White House director of legislative affairs, told reporters Wednesday.

“There was a huge risk to the economy,” Short said of regulations passed under former President Barack Obama. He said the Obama administration authorized a historic number of regulations and President Donald Trump is trying to use the CRA to roll back rules as he promised before his election.

Under the CRA, Congress and the White House can only rescind regulations approved in the last 60 days of the previous administration. Until this year, Congress had only used it successfully once before in 2001 to kill off a Labor Department ergonomics rule adopted under the administration of President Bill Clinton.

Two more rules are pending signature from the president to add to the ones previously signed including environmental and gun rights rulings. Once they are signed, Congress has only a few weeks left to make the final decision.