^{Editor’s note: This story was updated to reflect U.S. Rep. Randy Weber’s announcement in a Facebook post Wednesday evening that he was opposed to the GOP health bill.}

A day before the U.S. House is poised to take a historic vote on a bill that would overhaul former President Obama’s health care law, most Republicans in the Texas delegation are behind the measure with a few exceptions.

But dramatically, U.S. Rep. Michael McCaul, an Austin Republican who chairs the House Homeland Security Committee, withdrew his support for the proposed bill Wednesday, per the Huffington Post — reinforcing how unstable and perilous the vote counting process is proving for Republican leaders. 

Members are expected to vote on the bill Thursday night, but as of midday Wednesday, the bill was in enormous jeopardy. U.S. House Speaker Paul Ryan and President Donald Trump are pushing their caucus to pass the bill. If leaders fall short on their whip count, they are expected to pull the bill from consideration on the floor.

Of the 36 Texans in the U.S. House, 25 are Republicans. As of Wednesday morning, at least 15 had confirmed that they support the bill and several others said they were leaning toward backing it or remained undecided, according to recent media reports and inquiries from the Tribune.

Why are most Republicans from Texas supporting the bill? Some, like House Ways and Means Chairman Kevin Brady of the Woodlands and Michael Burgess of Lewisville, a key player on the House Energy and Commerce Committee, were closely involved in the crafting and selling of this legislation. 

And aside from McCaul, there are six other chairmen from Texas — and several more future possible chairmen — who have reason to want to avoid alienating Ryan, who wields strong influence over who is considered for those posts and other roles in the House.

Along with being universally condemned by Democrats in Congress, the bill has also drawn strong criticism from both moderates and conservatives in the GOP. As of Wednesday morning, a handful of Republican Texas members remained either opposed or undecided. Some did not respond to requests from the Tribune to clarify their current position.

U.S. Rep. Louie Gohmert, R-Tyler, from the get-go has posed the most hardened opposition among the 25 Texas Republicans in the U.S. House. Others like U.S. Reps. Will Hurd of Helotes remained undecided.