It’s OK to market stuff to captive movie theater audiences. But potentially enlightening or disturbing political and campaign pitches will be off limits this year on more than 20,100 screens at 1,600 theaters served by National CineMedia.

The No. 1 exhibition ad sales company says today that it won’t accept political messages in FirstLook, the pre-movie ad block that runs in venues owned by Regal, AMC Theaters, Cinemark and more than 40 other exhibition chains.

“There is no way to change the channel in a movie theater,” Sales and Marketing Presidnet Cliff Marks says. “So we must respect the fact that people go to the movies to enjoy the FirstLook preshow and lose themselves in the magic of the movies, and we believe that it is important to honor this entertainment experience.”

NCM’s potential piece of the $4.4 billion expected to be spent on local, regional, and national political ads in the 2016 election cycle is “not insignificant,” Marks says — although he declined to offer a figure. The company says it reaches more than 700 million moviegoers each year.

The policy to keep theaters politics-free is s slight shift: In the past NCM has run some political ads. Most were ones it deemed as “positive,” although in 2009 it presented spots from the U.S. Chamber of Commerce lobbying for legislation to restrict civil lawsuits. Marks told the New York Times that the campaign showing small business owners saying that they had been hurt by what they deemed as frivolous suits was “hard-hitting… It’s not a warm and fuzzy message, but one that says: ‘you need to know there is a problem.’ ”

Two years ago Texas GOP gubernatorial candidate Greg Abbott placed some of his 30-second spots in movie theaters in his race against Democrat Wendy Davis.

Marks says that after the last election NCM was “turned off by the negativity” in political ads across all media. The change is “a protection of our environment issue….Who wants to be the advertisement before or after that crappy negative ad?”

NCM could choose to not run negative spots “but there aren’t a heck of a lot of them out there, and — by definition — they’re divisive. When you come to the movies to escape reality, we’re not going to be the ones who are going to shove it back  in your face.”