Republicans generally supportive of President Donald Trump’s goal of dismantling the Education Department still have their doubts about key parts of his plans for the agency, with one GOP lawmaker vowing to stop the effort.

The Trump administration announced Tuesday it would work to shutter the department by transferring critical responsibilities to other federal agencies. The plan revolves around a series of agreements that spread responsibility for administering tens of billions of dollars in school-related spending across the federal government.

It’s a move that some congressional Republicans, school leaders and industry experts warn will be a major challenge not only to implement, but to also prove the administration’s approach will deliver efficient and lasting changes to the U.S. education system without creating a more complex web of bureaucracy.

“There might be some reorganizational things that make sense, if it allows for the department, the functions, to be carried out more efficiently, if they align better with the missions of other departments,” Rep. Kevin Kiley (R-Calif.) said. “But there’s a lot of really important things that the Department of Education does, and we need to make sure that it’s able to continue to do them, those services that need to be provided to taxpayers like charter school grants and kids with special needs.”

Rep. Brian Fitzpatrick (R-Pa.) went even further, saying in a statement he has “seen exactly how essential these programs are” and pledged to protect them.

“Altering them without transparency or congressional oversight would pose real risks to the very students they were created to protect,” he said. “I will not allow it — and I urge all of my colleagues to stand with me.”

The move could make good on the president’s often-touted promise to completely shutter the Education Department in the future, serving as a test case to Congress that a unified education agency is no longer needed. But a faulty implementation could put tens of billions of dollars and popular, high-profile programs — like those that support students from low-income families — at risk and siphon off support for a key part of the president’s education agenda.

It’s not clear how moving one agency’s duties to different parts of government will reduce bureaucracy beyond the deep staffing cuts the administration has already done.

Agency officials were unable to immediately say how many Education Department employees must be detailed to the Labor, State, Health and Human Services and Interior departments to carry out the agreements. The proposal raises new questions about how agencies will process and award federal grants. Implementing the transition could take months.

And the administration must communicate how all of its planned changes will work to the schools and states that rely on tens of billions of dollars for K-12 and higher education programs.

Briefing congressional offices ahead of Tuesday’s formal announcement, Education Department official Lindsey Burke described the administration’s bid to transfer work to other agencies as a first step, or “the engagement of the marriage.”

“Now the work begins,” she said.

At least one key Republican is fully on board with the administration’s approach.

“Bottom line, this is about putting students before bureaucracy,” House Education and Workforce Chair Tim Walberg (R-Mich.) said in a statement as he praised the Trump administration’s moves.

Senate education committee Chair Bill Cassidy (R-La.) did not answer a question about whether he was briefed on the department’s decision before the announcement, but said he “received assurances” the services the agency provides would remain intact.

But there’s an open question about how long the planned changes will last.

Education Secretary Linda McMahon told department employees who spoke with POLITICO Tuesday that its unprecedented agreements were temporary and could be made permanent by Congress when they are proven to work. This point was underscored by a department official who told POLITICO the idea was a “proof of concept strategy to show Congress how this can be done.”

But the top House appropriator on education issues had his doubts about the permanence of the Trump administration’s moves.

“If you’re going to completely try to do away with the Department of Education, I’d say yes,” they’d need an act of Congress, House Appropriations Labor-HHS-Education Subcommittee Chair Robert Aderholt (R-Ala.) said. “Moving them around, I think is a little bit more of a gray area. But I think in order to make it permanent, you’d need to have it by law because obviously the next administration could change it.”

And litigation from furious Democrats and their allies could slow the transition.

“They have to come to the Congress in order to do it, so we have to fight,” Rep. Rosa DeLauro, the top Democrat on the House Appropriations Committee said of the administration’s efforts to shutter the agency. “Maybe that’s going back to court.”

Education experts say the administration has to carefully implement its plans and warned its approach could create bureaucratic hurdles rather than eliminate them.

“The Department’s actions will expand federal involvement, rather than streamline it,” Josie Eskow Skinner, a former Education Department attorney for both Republican and Democratic administrations, said in a statement.

“States will now have to deal with the potentially conflicting or duplicative demands of multiple federal agencies with no central point of coordination or technical assistance,” added Eskow Skinner, who started an education law firm with other former department legal officials since leaving the agency earlier this year.

Jeanne Allen, CEO of the Center for Education Reform policy organization, said in a statement the transition “won’t be seamless, and it won’t succeed unless the new agencies clearly communicate with states, communities, and parents about their new flexibility — how funds can be better spent, and how to avoid getting snared in fresh compliance traps.”

“But shifting power closer to communities is the right direction,” she said.

The nonpartisan Council of Chief State School Officers said it encouraged the department to meet with state leaders to ensure any transitions happen as seamlessly as possible and congressionally approved funding flows without interruption to support students.

Angélica Infante-Green, Rhode Island’s education commissioner and a council board member, was more forceful.

“This decision is the latest in a long pattern of sudden, chaotic decisions at the federal level that have created widespread anxiety and confusion locally, undermining the stability our students and educators need to thrive,”she said in a statement. “Without a transparent timeline or clear details on how continuity of funds, technical assistance, and compliance oversight will be maintained, there is significant doubt that this transition will serve the best interests of children and schools.”