ABC’s “Jimmy Kimmel Live!” returns Tuesday night, but Nexstar and Sinclair are keeping the show off their affiliate stations.

Four Democratic lawmakers are opening a probe into Nexstar and Sinclair, two major TV station owners that are refusing to air Jimmy Kimmel’s late-night talk show amid criticism of his on-air comments about the assassination of Charlie Kirk.

In a letter, first obtained by NBC News, the lawmakers asked the corporate heads of both companies for more information about their decisions to pre-empt airings of ABC’s “Jimmy Kimmel Live!” and “how those decisions may relate to regulatory issues pending with the Trump administration.”

“If you suspended a late-night comedian’s show in part to seek regulatory favors from the administration, you have not only assisted the administration in eroding First Amendment freedoms but also create the appearance of a possible quid-pro-quo arrangement that could implicate federal anti-corruption laws,” the lawmakers wrote.