Republicans have revealed the details of their huge national tax rewrite - along with announcements of support that all but guarantee approval to give President Donald Trump the Christmas legislative triumph he has been aching for.
The legislation would slash tax rates for big business and lower levies on the richest Americans in a massive 1.5 trillion-dollar bill (£1.13 trillion) that the Republican party plans to muscle through Congress next week before its year-end break. Benefits for most other taxpayers would be smaller.
"This is happening. Tax reform under Republican control of Washington is happening," House Speaker Paul Ryan told rank-and-file members in a conference call.
"Most critics out there didn't think it could happen.... And now we're on the doorstep of something truly historic."
According to the 1,097-page bill released on late Friday, today's 35% rate on corporations would fall to 21%, the crown jewel of the measure for many Republicans. Mr Trump and Republican leaders had set 20% as their goal, but added a point to free money for other tax cuts that won over wavering politicians in final talks.
The legislation represents the first major legislative achievement for the Republican party after nearly a full year in control of Congress and the White House. It's the widest-ranging reshaping of the tax code in three decades and is expected to add to the nation's 20 trillion dollars (£15 trillion) debt. The tax cuts are projected to add 1.46 trillion dollars (£1.05 trillion) over a decade.
The bill would repeal an important part of President Barack Obama's Affordable Care Act - the requirement that all Americans have health insurance or face a penalty - as the Republican party looks to unravel a law it failed to repeal and replace this past summer.
Only on Friday did Republicans cement the needed support for the overhaul, securing endorsements from wavering senators.
Marco Rubio of Florida relented in his high-profile opposition after negotiators expanded the tax credit that parents can claim for their children. He said he would vote for the measure next week.
Mr Rubio had been holding out for a bigger child credit for low-income families. After he got it, he tweeted that the change was "a solid step toward broader reforms which are both Pro-Growth and Pro-Worker".
Senator Bob Corker of Tennessee, the only Republican to vote against the Senate version earlier this month, made the surprise announcement that he would back the legislation. Corker, the chairman of the Senate Foreign Relations Committee, has repeatedly warned that the nation's growing debt is the most serious threat to national security.
"I realise this is a bet on our country's enterprising spirit, and that is a bet I am willing to make," Mr Corker said.
The White House said Mr Trump "looks forward to fulfilling the promise he made to the American people to give them a tax cut by the end of the year".
The bill embodies a longstanding Republican philosophy that a substantial tax break for businesses will trigger economic growth and job creation for Americans in a trickle-down economy.
Sceptical Democrats are likely to oppose the legislation unanimously.
"Under this bill, the working class, middle class and upper middle class get skewered while the rich and wealthy corporations make out like bandits," said Senate Minority Leader Chuck Schumer of New York. "It is just the opposite of what America needs, and Republicans will rue the day they pass this."