Sen. Susan Collins, R-Maine, was caught on a hot mic Tuesday taking President Trump to task for his handling of the defense budget, questioning whether he knows how the Budget Control Act works or whether it exists.

Collins and Sen. Jack Reed, D-R.I., the ranking member of the Armed Services Committee, lamented Trump's lack of involvement in passing the budget and lifting spending caps set for 2018 by the BCA.

"I don't even think he knows that there is a BCA or anything, I really don't," Collins said in the candid recording shared widely online.

Both the House and Senate are proposing hikes in Defense Department spending, but Reed said Trump has been mum as lawmakers face the need to raise the caps in the BCA law or trigger sequestration, which means deep arbitrary cuts across the federal budget.

"If we don't get a budget deal, we're going to be paralyzed. DOD's going to have a problem," Reed told Collins. "Everybody's going to have a problem and [Trump] hasn't said one word."

Meanwhile, Reed said Trump's White House has been sending mixed signals about the budget to Congress, with Office of Management and Budget Director Mick Mulvaney pushing for funding for a border wall and other controversial issues while Treasury Secretary Steve Mnuchin suggested "clean" legislation.

"He was down at the Ford commissioning saying ‘I want them to pass my budget,' " said Reed, referring to Trump's speech at Newport News, Va., on Saturday to introduce the aircraft carrier Gerald R. Ford to the fleet. "OK, so we give him $54 billion and then we take it away across the board, which would cause chaos."

"Good point," Collins told Reed.

The president has proposed spending $54 billion beyond the budget caps as part of his defense budget, which was unveiled in May.

"Now, we need Congress to do its job and pass the budget that provides for higher, stable and predictable funding levels for our military needs that our fighting men and women deserve, and you will get, believe me," Trump said on Saturday. Trump also decried a "devastating defense sequester," which he said led to "deferred maintenance, a lack of investment in new equipment and technology, and a shortfall in military readiness."