President Obama plans to enforce a deadline for rail operators to install safety technology by the end of the year, despite warnings from railroads including Union Pacific Corp. and Amtrak that they can’t meet the mandate and would have to suspend some service without an extension.

President Barack Obama issued the third veto of his presidency Feb. 24 to reject legislation that would allow the Keystone XL pipeline to be built, escalating a battle over the project between the White House and Republicans in Congress.