Treasury Secretary Steven Mnuchin once promised "no absolute tax cut" for wealthy Americans.

But on Tuesday, he hedged on that pledge.

After Trump's election, Mnuchin told CNBC that wealthy Americans would get no "absolute tax cut." That would mean any cuts they did get under Trump's plan — including a big drop in the top income tax rate — would be offset by closing loopholes the wealthy use.

At the Peterson Foundation Fiscal Summit on Tuesday, Mnuchin appeared to temper expectations. He said delivering a "middle-income tax cut" is the White House's "intent," but he added that he "can't say what the results will be" because of Congress.

Mnuchin also said the Trump administration hopes to pass an overhaul of the U.S. tax system by the end of the year.

He stated clearly that "we're not going to get that done by August" — again backing away from an earlier statement on the original timeline the White House set for tax reform.