'Not a person who gets overly excited': Sen. Mark Kelly auditions to be Kamala Harris's VP

• Sen. Mark Kelly is the one and only senator on Kamala Harris's VP shortlist.
• Suddenly, he's become a center of attention on Capitol Hill. It's unusual for the Arizona senator.

It was just after noon on a Wednesday. The US Senate, known for its obnoxiously long votes, was 42 minutes into the first one of the day. Beneath the harsh glow of the fluorescent lights in the Capitol basement, senators and their staff shuffled to and from the elevators that would carry them up to the doors of the Senate chamber.

Suddenly, there's a shuffle. Someone important is coming through. A pair of photographers scramble into position to get their shot. Typically, this sort of thing precedes the arrival of someone who's been an object of the news cycle. Think Sen. Joe Manchin in the midst of Democrats' struggles to pass social spending legislation during the first two years of Joe Biden's presidency, or former Rep. George Santos in his early days on Capitol Hill. I crane my neck to get a glimpse of who it might be. It's Sen. Mark Kelly of Arizona.

Kelly is the one and only member of the United States Senate who has made it onto Vice President Kamala Harris's shortlist of potential running mates. Suddenly, Arizona's mild-mannered junior senator is under a massive microscope. "Mark Kelly, potential VP pick, plans to be in Arizona next week," reads a POLITICO headline from the last few days. (The Harris campaign is planning a blitz across several swing states with her yet-to-be-announced running mate next week. Kelly had said that "right now" he planned to be in his home state.)

Like the rest of the veep candidates, Kelly is caught in the most rushed vice presidential vetting process in modern American history, where auditions have taken the form of cable news hits and amped-up social media presences. Unlike the rest of the candidates, he's been doing it while holding a job that requires him to encounter reporters several times per day on the way to cast votes.

Suddenly, he's been on the phone a lot. Suddenly, the Arizona senator's Black Tesla outside the Capitol is an established stake-out spot. It's a natural draw for a Capitol Hill press corps whose attention has turned sharply toward a radically transformed (and suddenly exciting) presidential election. JD Vance may still be a senator, but Donald Trump's new running mate hasn't been seen at the Capitol in weeks. With Kelly, you're looking at the potential answer to the last big remaining question about the presidential election.

The media frenzy is an odd fit for the Arizona senator, whose reputation during his less than four years in the upper chamber has been that of a low-key, uncombative workhorse who's not exactly a go-to quote for reporters.

"He's the single most unflappable person I've ever met," Sen. Brian Schatz of Hawaii told me. "He's just not a person who gets overly excited in one direction or the other. He trusts his own preparation. He is, I'm not exaggerating, the most even-keeled politician I've ever met."

A less flattering way of putting it is that Kelly is kind of boring.

Being boring isn't necessarily a bad thing. The Senate is full of boring people. Politicians are probably a little too eager for the limelight these days. And being bland and unoffensive is what's helped Kelly win two successive Senate elections in a state that's gradually turning purple. That was especially true when he faced down Blake Masters — one of the GOP's more out-there Senate candidates — in 2022.

The conventional wisdom about Kelly is that, as a border-state senator, he might be able to shore up Democrats' credibility on immigration and border security. He also may be a good fit to go toe-to-toe with Vance, since he handily defeated a similar candidate just two years ago. He could help Harris win Arizona's 11 Electoral College votes. And there's his unique biography: An ex-astronaut who's married to former Rep. Gabby Giffords, the victim of an assassination attempt in 2011.

"Kelly would bring a lot to the table," Sen. Tim Kaine told me. The Virginia senator, who served as Hillary Clinton's running mate in 2016, went on to list Kelly's assets in a matter-of-fact way. "Child of two police officers. Merchant Marine Academy grad. Navy fighter pilot. Astronaut, meaning he has tremendous national security expertise. Battleground state with a Democratic governor, so he wouldn't give up the Senate seat. In a state that has a contested Senate race where his presence on the ticket could be helpful, and a very compelling personal story, not only in terms of his own public service background, but his intimate familiarity with the tragedy of American gun violence."

The one obvious weakness for Kelly is that he's never been a partisan warrior, a role that vice presidential candidates are often expected to play. It's a posture that other contenders have taken on gleefully, whether it was Minnesota Gov. Tim Walz essentially pioneering the "weird" epithet against Republicans or Kentucky Gov. Andy Beshear declaring that Vance "ain't from" his state. Kelly's trying it out too, making appearances on cable news shows and giving spicier-than-usual quotes to reporters around the Capitol. But he remains the soft-spoken man he's been since he arrived on Capitol Hill.

Leaving the first vote of the day on Thursday, Kelly had a clear shot to an idle Senate subway car, which would have whisked him back to his office and away from the badgering questions of a hungry press corps. In a few hours, senators would be leaving town until after Labor Day.

Then, he was intercepted by some interns. They wanted selfies. By the time he was done, the train was pulling away, and he was stuck waiting with a gaggle of about twelve reporters. One reporter asked him about Trump's latest attacks on Harris. Kelly called the former president "desperate." It was a line he'd already used a couple of times before.

"Folks have a, you know, option between a relic from the past, and somebody who is going to lead this country into the future and bring down the price of, you know, prescription drugs further, and help reduce the cost of childcare, improve health care, so many issues the American people care about," Kelly said. "It's so obvious that she's the person to bring us into the future."

He didn't seem eager to stick around, and the train was approaching. Would he be going home to Arizona after all? "I'm not going to be discussing my schedule," Kelly replied. Had he met with Harris's vetting team? "I'm not going to talk about any of that," he said.

"This isn't about me," Kelly said as the doors closed on him, repeating his stock response to the questions about his sudden vice presidential candidacy. "This is about beating Donald Trump."