As investigators sift through the wreckage of this week’s Amtrak train crash in Washington state, critics have begun questioning President Donald Trump’s recent efforts to roll back or delay finalizing U.S. rail safety regulations.

Making American railroads safer drew renewed attention after the passenger train derailed on Monday morning while speeding onto a bridge, killing three passengers and sending about 100 people to hospitals.

The accident occurred as the U.S. Transportation Department is reviewing rail safety requirements or proposals set under prior administrations. The White House has promised a sweeping effort to eliminate regulations throughout government and cut at least two existing regulations for every new one.

Earlier this month, the department reversed a decision requiring crude oil rail tank cars to be fitted with an advanced braking system designed to prevent fiery derailments. The requirement to install electronically controlled pneumatic brakes had been included in a package of safety reforms the Obama administration unveiled in 2015 following a series of deadly derailments stemming from the U.S. shale boom.

Senator Ron Wyden, an Oregon Democrat, called this month’s move “a senseless decision that endangers our communities by making oil by rail transportation less safe.”

The Transportation Department has defended the decision, saying the mandate’s costs would be three times as high as the benefits it would produce.

The agency has also delayed finalizing regulations proposed during the Obama administration to require railroads to run all trains with at least a two-member crew unless it got specific approval.

Train track safety inspections were another focus of the Obama administration, which said it planned to propose new rules to address “dangerous track conditions and defects” in order to prevent train derailments.

The Trump administration said in a document posted last week that the previous administration’s initiative had been moved to the “long-term action” list, meaning it does not plan any additional action for at least 12 months on the proposal and could abandon it completely.

In their defense, administration officials complain that Senate Democrats have for months delayed a vote on Ronald Batory’s nomination to head the Federal Railroad Administration, the top rail safety post, and say administration reviews of many railroad regulations are ongoing and no final decisions have been made as additional data is analyzed.

On Thursday, Senator Maria Cantwell, a Washington state Democrat, called on the Senate Commerce Committee to quickly convene a hearing on the state of Amtrak safety standards and federal rail safety regulation.

“The traveling public needs to know that Amtrak and its regulator, the Federal Railroad Administration, are doing all they can to protect the safety of passengers who use this vital piece of our transportation infrastructure,” Cantwell said in a statement, citing several major rail accidents over the last decade.

Railroads note that derailment rates have fallen in recent years and that the train accident rate is down 44 percent since 2000.

But the biggest pending railroad safety issue is a government mandate to install a technology called positive train control to prevent derailments. Had the technology been operational for the stretch of track where Monday’s derailment occurred, the crash might have been prevented.

In 2015, Congress delayed an end-of-year deadline for installing the technology by three years to the end of 2018 after lobbying by major railroads, including Warren Buffett’s BNSF Railway Co. The Transportation Department can extend the deadline again until the end of 2020.

Railroads had argued for years that the initial 2015 deadline set in 2008 was unworkable and that they had spent billions to develop the technology. While many passenger rail companies and freight rail companies have installed the system, CSX Corp., Norfolk Southern Corp and Canadian National Railway Co expect to complete the effort by 2020, according to the Federal Railroad Administration.

Senator Richard Blumenthal of Connecticut said Tuesday that the Trump administration must back the funding to ensure positive train control is implemented.

“The resources aren’t preventing its installation; it is the will and determination to do so. The failure of federal authorities to require and provide support for positive train control is a moral choice this nation has made,” Blumenthal said.

The National Transportation Safety Board has recommended the technology since 1970 and said that since then there have been more than 140 accidents across the country resulting in nearly 300 fatalities, more than 6,500 injuries, and millions of dollars in costs, which could have been prevented by positive train control.

Batory, the White House rail nominee, told a Senate panel in July he backed a regulatory approach to safety known as “performance-based regulations.” Critics say that would allow railroads to largely self-regulate and would eliminate specific safety technology requirements.

Republican Senator Deb Fischer of Nebraska in June proposed legislation requiring regulators to consider adopting a performance-based approach rather than setting specific regulatory requirements.

Republican Senator John Thune of South Dakota, who chairs the Senate Commerce Committee, said in a statement the Amtrak crash was not caused by the vacancy at the Federal Railway Administration, but said the agency needs leadership to advance safety issues and oversight.

“The time for playing political games with the leadership of this railroad safety agency should be over,” Thune said.

Thune on Thursday moved that the Senate unanimously confirm Batory, but Schumer objected and the motion failed.