Marco Rubio has replaced the head of the embattled United States Agency for International Development, as the Trump administration escalates its crackdown on foreign aid spending.

Rubio, who is putting Trump's "America First" stamp on foreign policy, said USAID will be brought under State Department control, citing "rank insubordination" and flagrant waste of tax money.

"We’re spending taxpayer money here. These are not donor dollars," Rubio told reporters in El Salvador. "These are taxpayer dollars, and we owe the American people the assurances that every dollar that we are spending abroad is being spent on something that furthers our national interests. And so far, a lot of the people who work at USAID have simply refused to cooperate."

Rubio confirms takeover

Each year, USAID spends billions of tax dollars on humanitarian relief in countries around the world. The Trump administration is targeting USAID as part of an effort to overhaul the federal government and trim waste.

The agency's defenders say it plays a role in projecting American soft power, but critics have blasted USAID as a globalist slush fund that has operated for too long as a self-governing entity.

In an interview during his Latin America trip, Rubio said USAID has acted as a "global charity" with Americans' money instead of prioritizing the national interest. Rubio, a former U.S. Senator, said the agency has been "completely unresponsive" to oversight from Congress for years.

"That cannot continue. USAID is not an independent, non-governmental entity. It is an entity that spends taxpayer dollars, and it needs to spend it, as the statute says, in alignment with the policy directives that they get from the Secretary of State, the National Security Council and the president," he said.

Rubio said he is the acting head of USAID, starting now.

"I'm the acting director of USAID. I've delegated that authority to someone, but I stay in touch with him," Rubio said.

Democrats declare "crisis"

Rubio has delegated authority to Pete Marocco, who wrote Trump's executive order freezing foreign aid. Meanwhile, thousands of USAID employees have been laid off and hundreds more locked out of their computers.

The agency's headquarters was also blocked to staff Monday as Elon Musk declared President Trump had given his blessing to close down operations.

Democrats, scrambling to catch their breath since Trump began his crackdown on government bloat, gathered outside of USAID's office Monday and declared a "constitutional crisis."

"This is a corrupt abuse of power that is going on," Sen. Chris Van Hollen (D-MD) said at a rally outside the building. "As my colleague said, it’s not only a gift to our adversaries, but trying to shut down the Agency for International Development by executive order is plain illegal."

Without a trace of irony, Trump's critics claim that he is installing a shadow government or illegal "fourth branch" by empowering Musk and his Department of Government Efficiency to slash the bloated, unelected federal bureaucracy. But, as Rubio noted, USAID already operates like a shadow government, without any check or control from the people and their elected representatives.

For too long, federal bureaucrats have taken for granted that they are not accountable to the people. With Trump back in charge, that's finally starting to change.