US President Donald Trump's administration has so far withheld at least $436.87 billion of congressionally approved funding, the top Democrats on the US Congress' appropriation committees said on Tuesday.
The frozen allotments span the federal government, according to the first estimate of the potential impoundments in the project led by Senator Patty Murray from Washington and Representative Rosa DeLauro from Connecticut.
These findings will be publicly posted in a tracker tallying the minimum the committees believe the administration is freezing or fighting in court to block, a committee aide said.
The administration has cited Musk's Department of Government Efficiency and the undoing of the federal government's diversity, equity and inclusion initiatives as reasons for blocking congressionally approved funding.
The administration's refusal to spend congressionally authorized funds amounts to a challenge of the US Constitution, which gives Congress oversight over spending, lawmakers said.
Trump challenged this idea on the campaign trail, as does the current head Office of Management and Budget, Russ Vought. The US Supreme Court also twice reaffirmed the limits on presidents' power to unilaterally cut spending.
Congress in the 1974 Impoundment Control Act codified a legal process for the executive branch to tweak spending levels by proposing cuts, called a rescission, which could be approved with a simple majority vote.
As of Monday, the administration has not submitted any rescission requests for Congress to codify, despite repeated requests from many congressional Republican lawmakers.