Its assessment comes a day after key Trump ally Elon Musk blasted the bill as a "disgusting abomination," giving fresh support to Republican deficit hawks who have been pushing back against the measure.

President Donald Trump’s big bill will cut taxes by $3.7 trillion but increase deficits by $2.4 trillion over the next decade

Bobby Kogan, senior director of federal budget policy at the Center for American Progress, a liberal think tank, said in an emailed statement that the Trump administration was already “illegally impounding additional funds,” as withholding money has “always been illegal without explicit Congressional approval.”

The Trump administration sent its first spending cuts request to Congress, asking lawmakers to swiftly eliminate $9.4 billion in funding for the Corporation for Public Broadcasting and various foreign aid programs.