When Donald Trump on Monday chose Senator J.D. Vance of Ohio as his running mate it excited populists — and unnerved some business elites. Later that evening, the president of the Teamsters, Sean O’Brien, gave a prime-time speech at the Republican National Convention. “Over the last 40 years, the Republican Party has rarely pursued strong relationships with organized labor,” O’Brien said. “There are some in the party who stand in active opposition to labor unions — this too must change,” he added, to huge applause. There’s something happening here — a real shift in the Republican Party. But at the same time, its official platform, and the conservative policy document Project 2025, is littered with the usual proposals for tax cuts, deregulation and corporate giveaways. So is this ideological battle substantive or superficial? Oren Cass served as Mitt Romney’s domestic policy director in the 2012 presidential race. But since then, Cass has had an evolution; he founded the conservative economic think tank American Compass, which has been associated with J.D. Vance and other populist-leaning Republicans, like Josh Hawley, Marco Rubio and Tom Cotton. In this conversation, we discuss what economic populism means to him, what it looks like in policy, and how powerful this faction really is in the Republican Party. Mentioned: “The Electric Slide” by Oren Cass “This Is What Elite Failure Looks Like” by Oren Cass “Budget Model: First Edition” by American Compass Book Recommendations: The Path to Power by Robert Caro Project Hail Mary by Andy Weir The Green Ember by S.D. Smith Thoughts? Guest suggestions? Email us at [email protected]. You can find transcripts (posted midday) and more episodes of “The Ezra Klein Show” at nytimes.com/ezra-klein-podcast. Book recommendations from all our guests are listed at https://www.nytimes.com/article/ezra-klein-show-book-recs. This episode of “The Ezra Klein Show” was produced by Annie Galvin. Fact-checking by Michelle Harris with Kate Sinclair and Mary Marge Locker. Our senior engineer is Jeff Geld with additional mixing by Aman Sahota and Isaac Jones. Our senior editor is Claire Gordon. The show’s production team also includes Rollin Hu, Elias Isquith and Kristin Lin. Original music by Isaac Jones. Audience strategy by Kristina Samulewski and Shannon Busta. The executive producer of New York Times Opinion Audio is Annie Rose Strasser. Special thanks to Sonia Herrero.