Sen. Elizabeth Warren, D-Mass., sat down with CNBC's John Harwood to discuss an array of issues, from President Donald Trump to the economy. Here, she talks about wanting to roll back the GOP tax cuts.

Q: If Democrats take the Congress, if you're in the White House, or both, would you like to see these corporate tax cuts repealed?

A: Yeah, I really want to see them rolled back.

Q: Back to 35 percent?

A: Well, it's not about the number. Here's how I look at budgets and taxes are at the heart of this. A lot of people think they're just numbers; they're not. They are the expression of our values. The values of the Republican Party that passed those tax cuts are to give $1.5 trillion away to the richest Americans and the biggest corporations, and let everybody else pick up the crumbs.

I think the right way to think about this is that we need a budget, we need a tax bill that works for all of us. So what I'd like to see is I'd like to see us strengthen America's middle class.

Q: What's too high for the top personal rate?

A: It's not about a number. That's what negotiations are all about.

Q: Is 50 percent obviously too high?

A: That's why you sit down and you negotiate over the numbers.

Q: When George W. Bush was president, his team articulated the view that it was a matter of right and wrong that you shouldn't have more than a third of your income taken. Do you feel similarly that it's wrong for more than half of somebody's marginal income to be taken?

A: Look, there was a time in a very prosperous America — an America that was growing a middle class, an America in which working families were doing better generation after generation after generation — where the top marginal rate was well above 50 percent.

Q: Ninety percent.

A: That's exactly right. But for me, the heart of the question is that you've got to ask, "What constitutes a fair share in this economy?" It depends in part on what the economy is.

Q: It doesn't strike you as obviously, "no, 90 percent, that's ridiculous. Can't be that"?

A: Ninety percent, yes; 90 percent sounds pretty shockingly high. But what I’m trying to get at is this is not about negotiating over specific numbers. It's not about negotiating before you go into the negotiations.

The Republicans wrote this tax bill behind closed doors. They didn't want any Democrats in the room. They sat down with their donors and with the lobbyists, and they decided on the rates by themselves.