WASHINGTON (AP) — The Republican tax plan will deliver a swift adrenaline shot to the economy that will send hundreds of billions pouring into federal tax coffers, the Trump administration asserts in a new analysis. But nonpartisan analysts make a less rosy projection of new revenue from the tax legislation now before Congress.

House and Senate negotiators are rushing to finalize the tax legislation and deliver the promised measure to President Donald Trump before Christmas. Trump will try on Wednesday to sell the American people on a GOP tax overhaul that is unpopular with many. His pitch: the plan will lift all economic boats, bringing a brighter future for taxpayers and their families, according to spokeswoman Lindsay Walters.

A Treasury Department analysis issued Monday estimated the tax legislation will generate a large part of $1.8 trillion in new revenue over 10 years.

Trump and Republican leaders in Congress have promoted the massive tax plan by promising that the tax cuts will boost the economy and create jobs. Their idea is that growth sparked by the legislation will let the tax cuts pay for themselves and not balloon the $20 trillion deficit.

Public polling shows many Americans are unhappy with the proposal. The separate bills recently passed by the House and Senate combine steep tax cuts for corporations with more modest reductions for most individuals.

Both measures would cut taxes by about $1.5 trillion over the next decade while adding billions to the deficit. They would bring the biggest overhaul of the U.S. tax system in 30 years, pushing into every corner of the U.S. economy and society. They would double the standard deduction used by most Americans to $12,000 for individuals and $24,000 for couples.

The administration’s estimate of new revenue from the tax plan is a lot higher than nonpartisan congressional analysts have projected. The Joint Committee on Taxation estimates that growth stimulated by the anticipated tax cuts in the Senate bill will generate some $408 billion in additional tax revenue over 10 years. For the House bill, the House-Senate committee sees $483 billion in new revenue.