"I think we should make sure they are exempt since they are not the big greenhouse-gas producers," said Baucus.

But Sen. Barbara BoxerBarbara Levy BoxerHillicon Valley: Ocasio-Cortez clashes with former Dem senator over gig worker bill | Software engineer indicted over Capital One breach | Lawmakers push Amazon to remove unsafe products Ocasio-Cortez blasts former Dem senator for helping Lyft fight gig worker bill Only four Dem senators have endorsed 2020 candidates MORE (D-Calif.), chairwoman of the Senate Committee on Environment and Public Works, said the amendment would lead to greater pollution and undermine the EPA. 

The vote was the first of three votes being held Wednesday afternoon that would limit the EPA's jurisdiction over greenhouse-gas emissions. Four other votes unrelated votes will follow.