One leaked proposal would have capped pre-tax contributions to traditional 401(k) plans at $2,400, dramatically lower than the $18,000 limit allowed this year.

That idea provoked a backlash from President Trump, who vowed on Twitter to protect the tax-preferred treatment of workplace retirement savings plans.

House Republicans are claiming the proposed bill will add $1.51 trillion in new deficits, which would keep the cost of the new tax cuts aligned with provisions Congress passed in a budget resolution.

The proposal would lower the corporate tax rate to 20 percent from 35 percent, effective next year. That rate would be made permanent under the proposal.

It also creates new tax brackets for households. The existing highest tax bracket of 39.5 percent will stay, but it will only be applied to income over $1 million under the proposal. Under existing law, the highest marginal rate applies to joint filers with income above $460,000.

For joint filers, income between $260,000 and $1 million will be taxed at 35 percent; income between $90,000 and $260,000 will be taxed at 25 percent; income between $24,000 and $90,000 will be taxed at 12 percent; households with less than $24,000 in income would not pay federal income taxes under the proposal.

The draft bill eliminates the Alternative Minimum Tax, doubles the standard deduction that individuals and families can claim, and would increase the child tax credit. A new $300 per-person tax credit would sunset after five years.

SALT deductions pulled

The first draft of the bill eliminates the existing deductions on state and local taxes, and caps the deductibility of property taxes at $10,000.

House Republicans from New York and New Jersey have threatened to vote against a bill that eliminates the so-called SALT deductions, which are valuable to taxpayers in high-tax states.

Eliminating SALT deductions could raise as much as $1.3 trillion over the next 10 years, according to the Committee for a Responsible Federal Budget.

The proposed bill reduces the mortgage interest deduction from the first $1 million of home loans to $500,000. The lower deduction would only apply to newly purchased homes.

That 401(k) and IRA contributions emerged unscathed is testament to the popularity of the deductions, and the concerted lobbying effort waged by a consortium of financial industry, employer, and consumer interests.

The Save Our Savings Coalition, which was formed earlier this year to advocate for protecting the existing treatment of contributions to retirement pans, counted the country's largest asset managers, AARP, and prominent employer advocates among its members.

"The proposal released today is good news for millions of middle-class families across the nation. Under this plan, American workers, families, and retirees will continue to have the freedom to choose the savings vehicle that best suits their needs," SOS said in a statement.

Other business advocates were less pleased. The National Federation of Independent Business said it won't support the proposal, on the grounds that its pass-through provision does not provide enough relief for small businesses. The proposed bill would set a 25 percent rate for small business owners' profits.

And the National Association of Home Builders slammed the bill, on the grounds that the lower caps on mortgage interest deductions will adversely impact middle-class families in expensive housing markets.

In a statement, Trump sought to preempt what is sure to be continued effort by some interest groups to protect existing deductions.

"The special interests will distort the facts, the lobbyists will try to save their special deals, and some in the media will unfairly report on our efforts. But my administration will work tirelessly to make good on our promise to the working people who built our nation and deliver historic tax cuts and reforms — the rocket fuel our economy needs to soar higher than ever before," Trump said.