Two major conservative outside groups are promising to support lawmakers who vote against the GOP’s health care overhaul.

Americans for Prosperity and Freedom Partners, which are both backed by the billionaire Koch brothers, are putting together a seven-figure fund that will go toward activity including paid media and direct mail for Republicans who vote against the bill. The legislation, formally known as the American Health Care Act, has been widely derided by conservatives both within and without Congress.

“The bill as it stands today is Obamacare 2.0,” said James Davis, executive vice president of Freedom Partners, in a Tuesday press release. “Republicans have been promising to fully repeal Obamacare since it became law. This bill doesn’t do that. We will stand with lawmakers who keep their promise and oppose this legislation – and work toward a solution that reduces costs and provides Americans with the relief they need and deserve.”

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The release goes on to say that Americans for Prosperity “has already begun a digital campaign thanking lawmakers who have come out publicly against the flawed legislation.”

The House is expected to vote on the health care bill on Thursday. Dozens of Republican lawmakers have come forward with concerns about the bill, which many do not feel goes far enough in repealing Obamacare. With Democrats unanimous in their opposition to the legislation, the GOP leadership, which supports the bill, can only afford to lose 21 Republicans when the vote takes place.

CBS News’ Steve Chaggaris contributed reporting to this story.