Donald Trump can clinch a majority of the delegates he needs to win the Republican presidential nomination. But his margin of error is razor thin, and even in a best case scenario, he likely won't get there until the last day of the primary season.
The polls could be wrong, but they do comport with signals from the ground: Wisconsin is Cruzing and feeling the Bern, and both candidates could ride the thermal updraft for the next two weeks.
Brandon Judd, president of the National Border Patrol Council, talks to Mary Louise Kelly about his group's endorsement of GOP front-runner Donald Trump.
Sen. Bernie Sanders raised $44 million in March, nearly all of it in tiny increments. Sanders says his fund-raising strategy guarantees independence from big-money interests.
Renee Montagne talks to Kei Kawashima-Ginsburg of Tufts University about the impact young voters have been having in the primary elections, and what that might mean in Tuesday's Wisconsin primary.
Wisconsin's primary is the only presidential contest this week. Mary Louise Kelly talks to columnist and commentator Cokie Roberts and Robert Costa of The Washington Post.
Republican politicians up for election are scrambling: What if Trump leads the ticket? NPR's Rachel Martin asks strategist Rob Jesmer how candidates are addressing the Trump issue.
Muslim voters say they're disheartened with some GOP candidates' comments about their faith this presidential campaign. But, they're trying to turn that disappointment political engagement.
Both Republican and Democratic primaries are being held in Wisconsin on Tuesday. Donald Trump and Hillary Clinton face different kinds of challenges in the state to maintain their leads.