Senate Majority Leader John Thune can afford to lose three Republican senators and still pass the bill, and there are more than that, right now, who have problems with it. Like the House, he will have to balance the concerns from moderate and conservative members of his conference.

The House Rules Committee pushes Trump's bill forward, facing Democratic resistance. Key issues include SALT deduction caps and Medicaid work requirements.

The White House says the House GOP's tax cuts will usher in an economic boom. Top economists say the upside is negligible.