(CNN) Democratic presidential candidate Sen. Kamala Harris in an interview with CNN on Tuesday responded to President Donald Trump's racist attack on four Democratic congresswomen of color by saying he "needs to go back where he came from and leave that office."

Harris, in an interview with CNN's Kyung Lah, also defended her position on " Medicare for All, " arguing that there would ultimately be no role for private insurance under her view of the sweeping health care plan because "almost everything will be covered." The California senator also pushed back against critiques lobbed by former Vice President Joe Biden comparing the push for Medicare for All to Republican efforts to overturn Obamacare.

Harris said Trump telling Democratic Reps. Alexandria Ocasio-Cortez of New York, Rashida Tlaib of Michigan, Ilhan Omar of Minnesota and Ayanna Pressley of Massachusetts to "go back and help fix the totally broken and crime infested places from which they came" was "un-American" and "unbecoming of the President of the United States."

"I think it defiles the office of the United States," Harris said. "It is irresponsible. It is hateful. It is hurtful. And he has taken the presidency to a new low."

Harris, the daughter of immigrants, said during a day-long swing through Iowa that she has been told to "go back to where you came from." But the senator added that it is "one thing to hear it in a school yard or on the street, it is another thing to hear that from the President of the United States."

"He needs to go back where he came from and leave that office and so that's why I'm running with the intention of making sure there will not be four more years," Harris said. "I don't think that we can survive having a President of the United States who uses whatever voice he has in a way that is about dividing and fueling hate in our country."

'Very little' role for private insurance

Harris said Tuesday that under her view of Medicare for All, there would be "very little" role for private insurance "because almost everything will be covered."

Harris has been less than clear on her view of Medicare for All since launching her campaign earlier this year. While she supports the Medicare for All bill in the Senate, Harris has also suggested that there would be a role for private insurance under her plan, pointing to coverage beyond what the overhaul of the health care system would cover.

Harris, at a CNN town hall in January, appeared to say she would eliminate private insurers as a necessary part of implementing the program. Harris and her aides later said that she was referring to the bureaucracy around health care and, since that town hall, Harris has said that her vision of Medicare for All "doesn't get rid of supplemental insurance."

But Harris raised further questions about her view of Medicare for All when, at last month's Democratic primary debate , she raised her hand in response to a question about whether candidates would "abolish their private health insurance in favor of a government-run plan." Harris raised her hand, but later said she misinterpreted the question.

On Tuesday, Harris said her view of Medicare for All "means that everyone will have access to health care and costs will not be a barrier."

"As it relates to private insurance, there will still be supplemental insurance, but yeah, transitioning into Medicare for All will at some point reduce the requirement for insurance because everyone will have access to health care," Harris said. "Under... my vision of Medicare for All, people will have covered what they don't now in terms of vision care, dental care, hearing aids."

Asked directly about the role of private insurance, Harris said it would be "to cover what is otherwise not covered."

Harris expanded upon her Medicare for All plan on Tuesday in a separate forum in Iowa, telling the audience that her view of Medicare for All will not be paid for through a middle-class tax hike, a break with Vermont Sen. Bernie Sanders, who has said taxes will go up for most Americans, including the middle class, but everyone will pay less in premiums.

"My vision of Medicare will not be about a middle-class tax hike," Harris said. "So, I'm not prepared to do that at all. And in that way, perhaps my position is different from some of the folks who are on the debate stage, but that is not what is going to happen."

Harris echoed that in her interview with CNN, stating bluntly, "I'm not prepared to engage in the middle-class tax hike."

Harris said she would pay for her plan by taxing Wall Street transactions.

"Part of it is going to have to be about Wall Street paying more. It's going to have to be about looking at how we and what we tax in terms of financial services. That's a part of it," she said. "But the other part of it is to understand that this is about an investment which will reap a great return on the investment. We can't only look at this issue in terms of cost without thinking about benefit."

Pushing back on Biden

Biden, who worked on passing Obamacare as vice president under Barack Obama, has attacked those Democrats who support Medicare for All, arguing that it would be "a sin" to do away with the former president's sweeping health care law to enact the new proposal.

"That's why I'm opposed to any Republican who wants to dismantle it or any Democrat who wants to dismantle it," he told CNN in an interview earlier this month. "The idea that you're going to come along and take the most significant thing that happened -- that any president has tried to do and that got done -- and dismantle it makes no sense to me."

Asked if what Harris is suggesting is an "elimination of Obamacare," Harris said, "Absolutely not," arguing that Medicare for All would build on the program.

"Listen, I will put my record up against anybody as having been a fighter for the maintenance and the sustainability of Obamacare," Harris said. "As attorney general, I mean, I'm sure on the debate stage, I'm the only one who went to court to fight to keep in place all of the benefits of Obamacare."

She added: "But like President Obama himself has said, he used the analogy of it being like a starter home. It was a profound public health policy and shift. It was incredible. The courage that he had and so many others to actually get it done and the wherewithal to get it done was profound. But now it's about taking it to the next step."

Harris also defended herself against Biden critiques on relying too heavily on using executive orders as president -- something the California Democrat pledged to do on prescription drug prices if, as president, Congress did not enact her plan within the first 100 days. Throughout her campaign, Harris has promised to use executive orders as president if Congress won't work with her on different priorities, including on changes to gun and immigration policies.

Biden has hit Democrats like Harris for saying, "If I'm elected, I'm going to issue an executive order to make sure the following things happen," arguing that it's disingenuous to pledge the same while also saying Trump is "abusing executive authority by using executive orders."

Harris rejected that criticism, noting that she would give Congress an opportunity to act before she deployed executive orders.

"Where it fails to act and where there is a longstanding and deep need for action by the American people, then where the authority exists in the executive branch to use executive power and take executive action, I am prepared to do it," she said. "I believe in just getting stuff done."