How does the popularity of a president’s policies impact his or her party’s electoral chances? Why have Latinos — and other voters of color — swung toward the Republican Party in recent years? How does the state of the economy influence how people vote, and which economic metrics in particular matter most?We can’t answer those questions yet for 2022. But we can look at previous elections for insights into how things could play out.John Sides and Lynn Vavreck — political scientists at Vanderbilt and U.C.L.A., respectively — have routinely written some of the most comprehensive analyses of American presidential contests. Their new book, “The Bitter End: The 2020 Presidential Campaign and the Challenge to American Democracy” — written with Chris Tausanovitch — is no exception.We discuss the core questions of 2020: How did Donald Trump come so close to winning? Why did Latinos swing toward Republicans? What role did Black Lives Matter protests have on the outcome? How did the strange Covid economy of 2020 affect the election results? And of course, what does all of this portend for the midterm elections in November?Mentioned:“Polarization and State Legislative Elections” by Cassandra Handan-Nader, Andrew C. W. Myers and Andrew B. HallIdentity Crisis by John Sides, Michael Tesler and Lynn Vavreck“Losers’ Consent” by Christopher J. Anderson, André Blais, Shaun Bowler, Todd Donovan and Ola ListhaugBook Recommendations:The Increasingly United States by Daniel J. HopkinsGroundbreakers by Elizabeth McKenna and Hahrie HanThe Loud Minority by Daniel Q. GillionRock Me on the Water by Ronald BrownsteinState of Terror by Hillary Rodham Clinton and Louise Penny“Bono Is Still Trying to Figure Out U2 and Himself” by David MarcheseThoughts? Email us at ezrakleinshow@nytimes.com. (And if you're reaching out to recommend a guest, please write  “Guest Suggestion" in the subject line.)You can find transcripts (posted midday) and more episodes of “The Ezra Klein Show” at nytimes.com/ezra-klein-podcast, and you can find Ezra on Twitter @ezraklein. Book recommendations from all our guests are listed at https://www.nytimes.com/article/ezra-klein-show-book-recs.“The Ezra Klein Show” is produced by Emefa Agawu, Annie Galvin, Jeff Geld and Rogé Karma. Fact-checking by Michelle Harris and Kate Sinclair. Original music by Isaac Jones. Mixing by Jeff Geld. Audience strategy by Shannon Busta. Special thanks to Kristin Lin and Kristina Samulewski.