The U.S. Chamber of Commerce is poised to endorse nearly two dozen freshmen House Democrats for reelection, triggering a revolt within the right-leaning organization and drawing fierce pushback from the group’s powerful GOP donors.

The decision represents a sharp departure for the traditionally conservative Chamber, which has spent over $100 million backing Republican candidates during the past decade, and it threatens to further complicate the party’s prospects in the November election while driving a split in the business community…

But the group’s donors and members are up in arms, with some threatening to pull funding and others openly venting their frustration. Some are raising the prospect that Chamber board members will quit in the weeks to come.

There is particular concern the Democrats in question do not have the pro-business record an endorsement would convey. State Chamber of Oklahoma President Chad Warmington wrote a letter Tuesday to national Chamber leaders fervently opposing the proposal to back Rep. Kendra Horn, perhaps the most vulnerable House Democrat in the country.