“Congress enacted this law, including the December 31, 2015, deadline, and we believe it is important that the Department of Transportation enforce the law that Congress passed,” Frank Benenati, a White House spokesman, said Wednesday, the day after lawmakers released a letter from Amtrak saying it might suspend some passenger service if the delay isn’t enacted.

House transportation leaders last week introduced legislation to extend the deadline for three years. House and Senate negotiators have been discussing ways to get the measure through both chambers. Benenati declined to comment on whether Obama would sign legislation extending the deadline because nothing has advanced in Congress.

Railroads have had seven years to install positive train control technology, which can slow or stop trains to avoid crashes, on their locomotives and tracks where passengers or hazardous materials move. The National Transportation Safety Board has been urging deployment of such technology for more than 40 years. The U.S. required it in a 2008 law passed by Congress and signed by President George W. Bush after a texting commuter train engineer in Los Angeles drove his train into a freight train, killing 25 people.

Three-Year Delay

Railroads are asking Congress to allow for a three-year delay to install the systems and another two years before they must be fully operational, saying the mandate has been expensive and they’ve faced regulatory delays from agencies including the Federal Communications Commission to get it installed. Senate legislation would require the system to be installed by 2018, though not necessarily fully operational. A House bill introduced last month would also require installation by 2018 and would lay out provisions for two more extensions.

Amtrak this week was the latest railroad to warn Congress it may halt or delay some service if the Dec. 31 deadline stays in place. While Amtrak says it will have the technology up and running on the track between Washington and Boston that it owns, passenger trains in most of the country run on freight rail tracks.

Freight railroads including Union Pacific and BNSF Railway Co., owned by Warren Buffett’s Berkshire Hathaway Inc., have told Congress they won’t be able to meet the deadline.