SPARTANBURG, S.C. — Sen. Kamala Harris railed on Tuesday night against President Donald Trump’s derogatory tweets about former Vice President Joe Biden over the weekend, calling them “contrary to the best interests of our country and the integrity of our country.”

At an MSNBC town hall, Harris said the tweets, including one in which Trump referred to himself as having smiled when North Korea’s Kim Jong Un “called Swampman Joe Biden a low IQ individual, & worse," were more examples of “why he should not be president of the United States.”

“The idea that this president on foreign soil attacked the previous vice president of the United States — I don't care what the differences on policy issues,” Harris said from the Wofford College stage. “I don't care what the differences in terms of party affiliation. It is wrong.”

The California senator and 2020 presidential candidate also rolled out her latest policy proposal, a plan to press for federal legislation that would require state and local governments with a history of having violated abortion rights under Roe v. Wade to receive Department of Justice approval for changes to future abortion laws.

“Are we going to go back to the days of back alley abortions? Women died before we had Roe v. Wade in place,” Harris said. “And so I'm going to tell you, on this issue, I'm kind of done.”

When asked by MSNBC’s Lawrence O’Donnell how she would acquire the 60 votes in the Senate necessary to pass such a proposal, Harris said voters must turn their attention to Senate races, along with the presidency, in 2020.

“Everything that we need to do is going to require 60 votes in the United States Senate, which is why I would say to everybody: 2020 is about the White House, [but] it's also about the United States Senate,” she said.

Harris also criticized Trump’s enduring trade hostilities with China, labeling the cost burdens on Americans as “Trump trade tax.”

“We are all paying a price for the policies, which have resulted in the Trump trade tax,” she said. “We are paying more for washing machines and shampoos. We are paying more in terms of our farmers having to eat the cost of having soybeans that they have been growing, rotting in bins. We are paying more in terms of autoworkers losing their jobs.”

Harris will make campaign stops in Greenville and Anderson on Wednesday, wrapping up her sixth stop to South Carolina since launching her presidential bid.