Debate night: everybody start your livers!

A narrow loss in a 2018 Texas Senate race made Beto O’Rourke a political star. He decided to try to ride that stardom all the way to the White House as a fresh face who combines charisma and an outsider persona with a fairly conventional Democratic policy agenda.

But while Beto’s campaign seemed almost painfully meta — he’s the guy who party professionals thought seemed like the kind of guy who voters would like — he’s running on a substantive agenda that in some ways comes the closest to representing the polar opposite of Trumpism.

He’s a NAFTA supporter and a longtime resident of a majority-Latinx border city who’s enthusiastic about immigration. His immigration platform commits him to going further than Trump or Obama in aggressively deploying executive power — protecting not only Deferred Action for Childhood Arrivals recipients but also their parents from deportation. He also calls for legislation that would dramatically expand a number of categories of immigration, from refugees to family unification to high-skilled workers.

He has also tried to fight his reputation as an ally of the fossil fuel industry (oil and gas are big in his home state of Texas) by becoming the first 2020 Democrat to release a climate change plan. He’s calling for $5 trillion in new investment and focusing tightly on ways existing law can allow a president to impose regulations that limit emissions.

But it’s really O’Rourke’s fulsome embrace of a politics of cosmopolitanism that makes him stand out from the rest of the field. While Bernie Sanders and Elizabeth Warren try to out-protectionist Trump and Joe Biden casts himself as an electability champion ready to win back the Rust Belt, Beto is the candidate of a hypothetical future Democratic Party that wins elections in Texas, Georgia, and Arizona powered by voters in the fast-growing suburbs of Dallas, Houston, Atlanta, and Phoenix.

Elizabeth Warren has a story she wants you to hear. She told it over and over across the state of Iowa on Memorial Day weekend. You could find the repetition a sign that she’s on autopilot, but in person, the opposite effect comes across: that this story is so important that she can’t afford to get a detail wrong. Her approach is chock-full of policy, sure; “I’ve got a plan for that” has become a rallying cry. Her flurry of proposals—for a wealth tax that would fund free public college and universal child care and pre-K, for a “Green Marshall Plan,” for canceling student debt, and for fighting the opioid crisis—is earning her headlines and driving her recent success with voters. In a national Economist/YouGov poll in mid-June, she grabbed second place in the Democratic primary field, behind former vice president Joe Biden and ahead of Vermont Senator Bernie Sanders. In a Monmouth poll of Nevada, the third state to vote in the Democratic primaries next year, she also climbed to second place, and in the latest Des Moines Register/CNN poll for Iowa, she was effectively tied with Sanders for second place. No doubt she’s helped by having the largest staff of all the Democrats; she has more than 50 people on the ground in Iowa, where I watched six meticulously executed events.

There have been breakout sensations, profound disappointments and examples of gritty resilience in the Democratic primary, but no candidate to date has been as simply confounding as the New Jersey senator, who has been sized up as presidential timber since he entered politics two decades ago. And few other contenders are under as much pressure to distinguish themselves at this debate, and the one next month, as he is.

Mr. Booker is more comfortable “leading with love,” as he often says in speeches, and he warns against “fighting fire with fire” when it comes to confronting President Trump.

It’s an approach that could pay off with Democratic primary voters, who surveys indicate are far more eager to find a candidate who wants to unite the country than merely fight against Republicans.

But it does not make for cable television or social media catnip, which has shaped the early contours of the race.

“It’s the opposite of viral,” said Jeff Link, a longtime Iowa Democratic strategist. “His message is totally different.”

This strategy has so far obscured Mr. Booker’s considerable attributes. He is a gifted orator, has a glittering résumé and enjoys longstanding ties to some of the most deep-pocketed donors in his party, yet he is stagnant so far in the polls. No other Democratic candidate but him has such a sophisticated organization and support network in Iowa, New Hampshire and South Carolina but is mired closer to zero than double digits in most every early nominating state.

Mr. Booker said he was not discouraged. “People who are usually polling this far down don’t succeed in winning the nomination but I think we’re going to do it,” he said in an interview Saturday, adding: “When people hear my message they convert.”