President Trump and Republican leaders plan to cut the top tax rate for the wealthiest Americans to 35 percent and dramatically reduce taxes on big and small businesses, according to details leaked to Axios.

Why it matters: It's the first glimpse of the tax reform plan agreed upon in secret between the "Big Six" congressional leaders and administration officials. It forms the starting point of the tax reform process, which will play out over the coming months.

The big change: The GOP leaders and the White House plan to cut the top tax rate for “pass through" businesses from 39.6 percent to 25 percent. (Most businesses in America do not pay the corporate tax. Sole proprietors and other mostly smaller businesses see their profits “passed through” to their owners and taxed at the individual income rate.)

The so-called "Big Six" tax framework — named because it's been hashed out behind closed doors between six top Republicans and administration officials — will set up a clash with Democrats over the tax breaks that apply to large corporations and upper income Americans.

Most Democrats have already drawn a red line on tax reform: 45 out of 48 Democratic senators signed a letter saying they wouldn't support any tax bill that adds to the deficit or offers new tax breaks to the wealthiest Americans.

But Republicans are desperate for a win and appear on course to fund tax cuts with a blend of deficit spending and the closing of loopholes. They will dare Democrats, especially the 10 senators up for re-election in states Trump won, to vote against tax breaks for their constituents.

What's next: President Trump is planning to give a speech unveiling the Big Six framework in Indiana on Wednesday, three sources said. The framework is the starting point for the tax reform process. It reflects the shared view of the Big Six, but it will inevitably change substantially as it goes through the normal legislative processes in the House and Senate.

(The "Big Six" are House Speaker Paul Ryan, Senate Majority Leader Mitch McConnell, Treasury secretary Steven Mnuchin, White House economic adviser Gary Cohn, and the chairmen of the two tax-writing committees — Senate Finance Committee chairman Orrin Hatch and House Ways and Means chairman Kevin Brady.)

The details, per three sources with knowledge of the plan:

Top individual tax rate cut from 39.6 to 35. The current seven income tax brackets collapsed to three, as part of simplification. (Axios hasn't obtained the other two rates.)

Axios can confirm that the Big Six agreed to cut the corporate tax rate from 35 percent to 20 percent. That key detail leaked last night to the Washington Post. (Trump has said he wants the corporate rate to be 15 percent.)

The Big Six framework is also expected to include guardrails to prevent wealthy people from artificially lowering their income taxes by rearranging their affairs to get taxed at the small business rate.

We can confirm, too, WashPo's reporting that Republicans plan to double the standard deduction — a boost for the middle class and a key component of simplification.

These Big Six decisions have been held incredibly tightly, but details began leaking out around Capitol Hill on Friday night and the corporate rate was first published by the Washington Post's Hill team. By Saturday, influential figures on K Street were beginning to learn more details.

Some problems the Big Six could run into: