What makes Mitt run (and run and run)?

What makes Mitt run? That's the question I put to Scott Helman, an editor at the Boston Globe and longtime Mitt-storian. (Helman co-wrote "The Real Romney" about the life and times of the two-time presidential candidate.)

Our conversation -- conducted via email and lightly edited for flow -- is below.

Cillizza: Mitt Romney is running for office again. That's his 5th run -- Senate, governor, 2 presidentials, Senate again -- since 1994. What makes Mitt run?

Helman: A deep sense of service, a surplus of ambition, and more than a little confidence in his own abilities.

Remember that Romney was born into a family where service and leadership were paramount. His father, George, served three terms as governor of Michigan, led a car company, and was a Cabinet secretary under President Nixon. Service is also central to Mormon practice, manifesting not just in tithing -- giving 10 percent of your income -- but in the value placed on performing acts of grace for others.

I can't tell you how many stories I heard of Romney intervening to help people in a bind. Not all of these offers of help were well received; they can have a patronizing quality. But it's who Romney is, through and through.

On a more prosaic level, he's also just a busybody. It was always difficult to imagine him puttering around the house, satisfied playing the role of graying retiree.

Cillizza: Romney thought about running for president a 3rd time in 2016 and passed. Why Senate? And why now?

Helman: Because it's there. After two bruising, exhausting presidential runs, surely it's appealing to him to have (presumably) a glide path to the Senate in a state where he's very well regarded.

In business and politics, Romney has always been known for picking his spots. Call it savvy strategy or naked opportunism -- or maybe both. But an open Senate seat in Utah is probably as no-brainer as it gets if Romney still wants a seat at the table in national politics.

I think it's fair to assume he's also genuinely and profoundly concerned about the state of the country. The Romney ethos could hardly diverge more from the Trump ethos, especially in terms of character and temperament. I have to believe part of Romney's motivation is a fierce desire to correct America's course, however difficult that may be as a mere voice among 100 in the Senate.

Cillizza: Romney seems to represent an old school version of the GOP. What the party looked like before Trump. Is his Senate race an attempt to preserve that version of the party?

Helman: I think that's probably true to a degree, yes.

Keep in mind, though, that however much Romney seems to embody a different GOP, his political philosophy has been pretty malleable over the years. His father, George, was known as a political moderate. So was Mitt when he ran for Senate against Ted Kennedy and then for governor of Massachusetts. It wasn't until the 2008 Republican presidential primary -- when John McCain and Rudy Giuliani made for a crowded centrist wing of the party -- that Romney pivoted hard to the right. (Hard enough that he memorably styled himself as "severely conservative.")

So while I think he would be something of a throwback, it's not like his political identity has been pure and entirely consistent. Political ideology aside, though, he would certainly look to bring civility, sobriety, and competence back to American politics.

Cillizza: Romney's relationship with Trump is complicated. He was a vociferous critic during the campaign. But then he seemed willing to serve as Secretary of State. What does Romney actually think about Trump?

Helman: I don't want to pretend I know what he really thinks. But everything I've learned and observed about Romney suggests he would hold Trump in very low regard. He said as much during the 2016 campaign.

It was hard to know what to make of the overtures about secretary of state. Was Romney willing to cave purely in the name of ambition? Or was he just showing a willingness to hold his nose for the sake of the country, so that there might be an adult in the Cabinet? Trump's personal conduct -- the bullying, the prejudice, the lack of curiosity, the boasting about sexual conquests -- could not be any further from Romney's. I mean, we're talking about a guy, in Romney, who has lived according to a very strict moral and behavioral code. It's hard to imagine a bigger contrast.

Cillizza: And will we hear that from him in the Senate?

Helman: I don't know, honestly. Romney definitely comes in with some leftover political capital, and thus some independence. Usually, of course, people go from the Senate to the presidential campaign trail, not the other way around. So he'd have an instant platform that other freshman senators would not.

At the same time, there have been other independent-minded politicians who show up to the clubby quarters of Congress and discover that independence can be a heavy cross to bear. And Mitch McConnell has proven himself to be a canny, durable Senate leader who will do what it takes to advance an agenda. Romney has never served in a legislative role, and in the past he's shown an allergy to that kind of deal-making and arm-twisting. I'd very curious to see how he handles that pressure.

Cillizza: Finish this sentence: "In 5 years, Mitt Romney will be ___________." Now, explain.

Helman: "frustrated by his relative powerlessness in the Senate but enjoying his renewed visibility in American politics."

Romney's an executive by nature. He'll bristle at the limitations of being one voice among many. But he'll find a way to contribute -- he always does -- and relish the role as elder statesman.