Sen. Elizabeth Warren, D-Mass., sat down with CNBC's John Harwood to talk about an array of issues, from President Donald Trump to the economy. Here, she tackles the question of whether Democrats should try to impeach Trump if they take back Congress.

Q: After the 2018 elections, if Democrats have one or both houses, should the imperative for Democrats at that point be to block things that the president's doing that you don't like, or to try to impeach him and get him out of office?

A: Oh look, I take the impeachment question very seriously. But what that means to me right now is that the special prosecutor, Mueller, needs to be able to finish his investigation and present all of his results to the American people.

Q: But you don't see anything right now that suggests to you that he should be impeached?

A: That's not the question. We have an ongoing criminal investigation. It has already resulted in more than two dozen indictments or guilty pleas. We need to get the investigation finished. Mueller needs to be able to do this with no interference — Republicans, Democrats, nobody. Let him finish his investigation, present it to the American people, and then we'll see what we've got.