Mnuchin walked back this key piece of Trump's tax plan, CNBC's Robert Frank says — Larry Kudlow disagrees

Here's how potential tax reform rules affect the middle class

President Donald Trump 's much-anticipated tax reform plan may, in fact, give tax breaks to the wealthy, CNBC's Robert Frank said Thursday.

Frank said Treasury Secretary Steven Mnuchin, in an exclusive interview with CNBC, appears to have walked back a previous statement that there would be no absolute tax cut for the wealthy.

"He was very clear that there would be no reduction in the taxes of the upper-income taxpayers," Frank said on "Squawk Box."

"When (CNBC Squawk Box anchor) Becky [Quick] asked him that this morning, he kind of walked it back. [He] said, 'Well it's our objective ... we haven't finalized anything.' What I don't understand is what's wrong with giving tax breaks to the upper-income earners if that's what you're doing?"

Larry Kudlow, a CNBC senior contributor, disagreed with Frank's assessment. He said the middle class is the winner in Trump's plan.

"Eighty percent of this bill revolves around large- and small-business tax cuts. And the biggest winner is middle-income wage earners," Kudlow said.