Congress demands answers after safety regulator misses deadline on potentially lifesaving new rules for vehicle seats

The nation's top auto safety regulator was given two years by order of Congress to make vehicle seats stronger, following a multi-year CBS News investigation. But the National Highway Traffic Safety Administration, or NHTSA, missed the deadline.

Now, 10 U.S. senators are demanding answers.

"I'm going to turn up the heat on NHTSA," Sen. Ed Markey of Massachusetts, told CBS News in a recent interview. "It shouldn't be hard. This is actually very simple. We're not trying to put somebody on a mission to Mars. We're just trying to make sure kids in the back seat are protected."