Over the course of the weekend, my colleagues and I spoke to dozens of voters, activists and officials, and so many candidates. Here’s what we learned about the state of the Democratic primary contest:

• The race has firmly separated into tiers. Tier one: Joe Biden, Elizabeth Warren, Kamala Harris and Mr. Sanders. Tier two: Ms. Klobuchar, Cory Booker and (maybe) Pete Buttigieg. Then, there’s everyone else. Here’s how Sue Dvorsky, an influential Democratic activist who endorsed Ms. Harris this weekend, put it: “There’s a tier of likely. There’s a tier of possibles. And then there’s a tier of unlikely.” Does that mean no one can climb the ranks? Of course not. But in such a crowded field, it won’t be easy.

• Ms. Warren is having a moment. In our discussions with voters, nearly everyone said they were considering backing Ms. Warren. She got the biggest crowd at the state fair and huge applause at a party fund-raising dinner on Friday night, and attracted hundreds to her events across the state. Of course, a summer surge doesn’t necessarily mean a winter win. Just ask Howard Dean.

• Mr. Biden leads the polls. But that may be shifting. As Allison Engel, a former Democratic aide in the state who now volunteers for the party, told me: “He’s the candidate that people think other people are going to vote for.” An informal survey of county chairs found plenty of concerns about his age and agility. Many Democratic insiders attribute his lead to name identification. They suspect his candidacy could fade, particularly if he keeps misspeaking, as he did several times this weekend.

https://www.nytimes.com/2019/08/12/us/politics/on-politics-iowa-fair-booker-ferris-wheel.html?searchResultPosition=2