Transportation Secretary Elaine Chao on Thursday said President Trump’s plan to speed up environmental permitting reviews is a key piece of the administration’s infrastructure proposal.

Chao, in testimony before the Senate Environment and Public Works Committee, said the private sector is frequently deterred in investing in public infrastructure projects because of slow permitting.

The Trump administration’s proposal aims to spend $200 billion in federal funding to spur a total of $1.5 trillion in infrastructure investment, with states, localities and private industry covering the difference.

“While there is a great deal of enthusiasm from the private sector to participate, one of the hurdles they face is the lack of ready projects,” Chao said. “If the permitting process can be sped up, it will allow more projects to be available for the private sector to invest.”

Trump already has acted on his own to encourage faster approval of infrastructure projects.

He issued an Aug. 15 executive order that calls for "timely decisions" on projects with the goal of completing "environmental reviews and authorization decisions for major infrastructure projects within two years."

Indeed, Chao says the Transportation Department removed more regulatory restrictions than any other agency in Trump’s first year, a concept Republican lawmakers support.

“Streamlining will allow needed projects to start quicker and finish faster for lower costs,” said Sen. John Barrasso, R-Wyo., chairman of the Environment and Public Works Committee. “It shouldn’t take a decade to permit a project that takes only months to build.”

But the Trump administration wants Congress to expand on those efforts, to the alarm of Democrats.

Democratic lawmakers have panned Trump’s proposal to “streamline” environmental reviews, arguing that doing so would harm protections for natural habitat and endangered species.

The infrastructure plan says environmental reviews must be conducted in no more than 21 months. It calls for changes in how the government conducts the reviews, including streamlining the National Environmental Policy Act’s requirements and potential changes to the Clean Water and Clean Air acts.

Sen. Tom Carper of Delaware, the top Democrat on the committee, said there are some “good ideas” in Trump’s proposed permitting reform, but he argues the administration is going too far.

“I’m disappointed by the degree to which the administration is focusing on sweeping rollbacks to our nation’s bedrock environmental protections,” Carper said. “I’m committed to delivering projects quickly, but simply gutting environmental protections does not achieve time savings. Doing so could potentially put our communities at risk.”

Carper noted Congress has already enacted permitting reforms in previous transportation bills from 2012 and 2015. The 2015 bill, known as the FAST Act, included a provision imposing a two-year limit for filing lawsuits against projects.

That law, passed by bipartisan margins, also directed courts to consider the effects of decisions on jobs, created an interagency council to coordinate permitting, and established expedited permitting timetables.

Carper argued the Trump administration has not fully implemented these laws, by not appointing an executive director to the interagency council and delaying grant decisions for projects.

“One of the best ways to speed up projects is provide long-term funding and program certainty,” Carper added, questioning why the Trump administration in its fiscal 2019 budget has proposed cutting funding for the Transportation Department’s permitting office.

The Trump administration has suggested the 2015 law was too narrowly tailored because it focused mostly on NEPA reviews but did not tackle other permitting processes handled by various agencies.

NEPA mandates that agency decisions that could have an environmental impact on the nation’s air, water or wildlife habitats include a scientific analysis of potential effects.

The Trump plan aims to reduce the time a state has to issue water permits, known as “section 401” certificates, required under the Clean Water Act to build interstate natural gas pipelines.

States such as New York have used this provision to halt pipeline projects.

Trump's proposal also allows some revenue from energy development on public lands to be used to pay for capital and maintenance costs of infrastructure built on federal lands.

Additionally, the proposal would end the EPA’s ability to review environmental impact statements devised by other agencies.

Other proposed changes to permitting include requiring federal agencies to conduct concurrent environmental reviews, rather than consecutive reviews, to speed up the process. The White House argued that would reduce duplicative reviews by letting the main agency with expertise lead the process.