South Bend, Ind., Mayor Pete Buttigieg, who is also a Democratic candidate for president, in Austin on March 9. (Callaghan O'Hare/Bloomberg)
Opinion writer

What do Democratic presidential primary voters want? There’s no one answer, of course. But the entry of all these candidates — former representative Beto O’Rourke (Tex.) is the latest, and former vice president Joe Biden looks ready to jump in any day — makes one wonder what we expect a president to know, to be, and to have done by the day he or she walks into the Oval Office.

It’s the unlikeliest candidacies who bring that question into relief.

Let’s begin with a taxonomy of the contenders. In one group we have those with the traditional set of qualifications — service as governor, senator or vice president. This is what, until a few years ago, it was assumed you had to have on your résumé to even consider running for president. The candidates who qualify are Biden, Sens. Elizabeth Warren, Cory Booker, Kamala D. Harris, Kirsten Gillibrand, Amy Klobuchar, Bernie Sanders, Gov. Jay Inslee, and former governor John Hickenlooper.

Then you have what we might call the reachers — people with some federal government experience (especially in the House) but, in a previous era, would have been told to move up a bit before making a run. This group includes O’Rourke, former representative John Delaney, former HUD secretary Julián Castro, and Rep. Tulsi Gabbard.

Then we have the leapers — those without federal experience or a governorship who are jumping a few steps to seek the presidency. These include Pete Buttigieg, Marianne Williamson, Andrew Yang, and Wayne Messam. Of these, only Buttigieg is getting any substantial media attention.

You probably haven’t heard of a couple of people on that last list, and they’re surely jealous of Buttigieg, who is the mayor of South Bend, Ind. Williamson is a self-help guru, and Yang is an entrepreneur and leader of a nonprofit, so many dismiss them out of hand since they’ve never held public office. Messam, on the other hand, is the mayor of Miramar, Fla., which at 140,000 residents is somewhat larger than Buttigieg’s home city, which has a little more than 100,000.

What makes the mayor of a small city think his next job should be running the country? You’d have to ask them (and wade through a bunch of pablum in response), but if you want to blame someone you could start with former president Barack Obama. When he first ran for president in 2008, Obama had only a few years of experience in the Senate and everyone thought it was way too soon, but he proved that with enough talent and some good timing, experience didn’t matter. And though he was a once-in-a-generation politician, every politician thinks they’re just dynamite and that there is no limit to the support they can get if they only have the opportunity to talk to people.

Right now, Buttigieg is getting attention not only because he’s a genuinely impressive guy, but because he did something very shrewd when he ran to be the chairman of the Democratic National Committee in 2017. Even though he didn’t win, it put him in front of a bunch of influential people in the party and the media, and because many were taken with him, they were ready two years later to see his presidential candidacy as something worth considering.

There’s another factor that makes voters more likely to consider a young person such as Buttigieg, who’s only 37 years old. In the 2018 midterm elections, we saw a wave of new Democrats elected to the House (and to state offices), many of whom were quite young. Rep. Alexandria Ocasio-Cortez (D-N.Y.) is the most visible example; at just 29, she’s the star of the freshman House class, not just because she’s media-savvy but because she’s offering ideas meant to challenge the status quo in ambitious ways.

This is part of Buttigieg’s appeal, too. When asked on MSNBC’s “Morning Joe” what his central message is, he replied, “We need a generational change.” At the moment, the idea of electing someone young may not seem as outlandish as it might have not too long ago.

Nevertheless, any candidate jumping a few levels to seek the White House has an extra responsibility to demonstrate that he or she is ready to be president. If you have served as a governor, you’ve managed a large government, dealt with a legislature and confronted an array of problems both large and small. If you’re a senator, you’ve had to understand foreign and domestic issues and learned about how government works. In both cases, you’ll have a record we can investigate.

That goes for someone such as O’Rourke, too. He was a relatively undistinguished congressman before he ran an exciting Senate campaign in Texas, but he should be able to explain why, despite his limited experience, he can do the job better than a candidate with more time in government and pretty much the same policy agenda.

So while my general position is that anyone who wants to run for president should go right ahead, I would argue that candidates such as Buttigieg and O’Rourke ought to have some extra convincing to do. They need to show that they’re conversant with the problems the federal government confronts, and that they have clear ideas about how to govern from the White House.

Of course, the other candidates should do that, too.

Read more:

Greg Sargent: How Democrats can defeat Trump and his ugly ideas, according to Pete Buttigieg

E.J. Dionne Jr.: The reality and limits of Beto-mania

Kathleen Parker: Beto O’Rourke’s 2020 campaign is a youthful folly

Karen Tumulty: What does Pete Buttigieg bring to the table? Experience — really.