“I have a D-minus lifetime voting record from the NRA” isn’t an applause line in most rooms in Texas, but it earned Bernie Sanders a big cheer at SXSW during his one-on-one session with CNN correspondent Jake Tapper on Friday. It was one of many lines that got the popular Vermont senator applause from a packed room.

“The problem with Donald Trump,” Sanders said—those words alone caused an eruption from badge-holders—is that “he lies all of the time. What he says on Monday is not necessarily what he says on Tuesday.” He discussed the DACA negotiations, and called the idea of funding a border wall—which he voted for, “very reluctantly,” in order to secure the DACA deal—”one of the stupidest ideas in the history of the world.” Tapper pushed the Vermont senator on the issue: does he support shutting down business in the Senate until the DACA issue is resolved? Sanders had a strong response: he voted against one of his own bills in order to send the message that the most important issue was figuring out how to resolve the uncertainty that the Dreamers live with. The DACA program quietly ended on Monday, although the Trump administration is under federal court order to continue issuing work permit renewals under the program.

Tapper turned the conversation to the primary race in Texas’s seventh Congressional District, which, in February, much to the surprise of many Texans, became a national topic of conversation when the Democratic Congressional Campaign Committee jumped in to slam candidate Laura Moser, a Twitter-savvy campaigner from the Sanders wing of the party. (Moser found herself pulling enough of the vote to make it into a runoff, despite—or perhaps because of—the increased scrutiny.) Sanders had spoken out about the DCCC’s involvement in the race, and Tapper asked the senator why he felt so strongly that the committee shouldn’t interfere.

“I think the average American is disgusted with the current political process. What politics is supposed to be about are candidates having serious discussions about the issues facing the American people,” Sanders said, citing health care costs and availability and the cost of higher education. “There are a million issues out there that we should be discussing. But politics is about, ‘You want to run for office? First thing you should expect is that your opponent will be spending a lot of money doing opposition research against you to see if they can come up with something stupid you may have said, or something personal about you or your family, and then they’ll run a thirty-second ad saying ‘This person said this stupid thing, vote for the other guy,’ and then the issues will not be talked about.”

It was probably the most fiery moment from Sanders, as he spoke of his disgust for what he characterized as a deeply unserious approach to politics. “I detest that type of politics, and I think most Americans do,” he said. “And then when you have the DCCC actually doing opposition research on a serious and strong candidate for the United States Congress, when the DCCC is engaging in negative attacks against a responsible candidate, that is absolutely unacceptable and has got to end.” Tapper, pushing back, asked if the DCCC had a responsibility to find and support the strongest candidates, which Sanders responded to like a fastball right over the center of the plate: “Having gone through a little bit of that myself, you want to know who the strongest candidate in that district is?” Sanders said, referencing his experience in the 2016 presidential primary against Hillary Clinton. “Let the people make that decision.”

During the Q&A, the presidency came back up — specifically, whether Sanders is planning on running for president again in 2020, in a campaign that won’t feature Hillary Clinton as a primary opponent. Sanders demurred—”we’re a long, long way from the 2020 elections,” he said—and instead discussed his travel schedule for the rest of the weekend, and why he’s excited to be in Texas. “The reason we are going to conservative areas is to increase turnout, so that Democrats can take back the House and Senate in 2018,” said Sanders. “That’s where my focus is right now.”