Karl Rove, who served as senior adviser to President George W. Bush, said the biggest stumbling block for Republicans in getting tax reform started in Congress is the House Freedom Caucus.
Rove made his remarks in a column for The Wall Street Journal.
Rove noted the House and Senate must pass a budget resolution setting spending levels. He said the resolution would set the size of the tax reform.
"Republicans could cobble together a budget resolution setting up a strong tax reform, which in turn would juice the economy and redeem the GOP in the midterms," he said.
But Rove added: "The biggest obstacle is the House Freedom Caucus. This group of just over 30 Republican congressmen has already slowed up the process by threatening to vote with Democrats against the GOP budget resolution unless they can see and approve, in advance, every major provision of the tax-reform bill.
He claimed caucus members "say they'll flake on the budget resolution" if the tax reform package includes "full, immediate expensing of business investment."
"But if that's agreed to, they'll have more demands," he said.
"What they want is for their caucus to dictate the details of tax bills to the House Ways and Means Committee, the Senate Finance Committee and the Republican majorities on both sides of Capitol Hill. Their approach is to make demands while threatening to join Nancy Pelosi in opposing the budget resolution unless they get their way."
And he said if caucus members carry through on their threat, the budget resolution could be voted down and doom tax reform.
"No doubt, following their M.O., the group's members would then blame the GOP leadership," he said. "Even if the resolution passes, the Freedom Caucus's shenanigans may delay tax reform until 2018. These lawmakers are demonstrating once again that the freedom they most prize is freedom from the responsibility of governing."