The advocacy groups helmed by Charles and David Koch have unveiled a new pool of money for advertisements, field programs and mailings that would exclude those who vote for the health care bill they oppose on Thursday. The effort, which they described as worth millions of dollars, is an explicit warning to on-the-fence Republicans from one of the most influential players in electoral politics not to cross them.

The Koch-aligned networks oppose the bill because they think it does not do enough to scale back former President Barack Obama’s health care policies.

“We want to make certain that lawmakers understand the policy consequences of voting for a law that keeps Obamacare intact,” Americans for Prosperity president Tim Phillips said. “We have a history of following up and holding politicians accountable, but we will also be there to support and thank the champions who stand strong and keep their promise.”