Five days ago, Jeb Bush was outside a hotel in Berlin, straining to evince something other than abject dread at the prospect of running for president.

He stood, rigid and erect, in front of a semicircle of American political reporters as they peppered him with questions about the recent shake-up inside his campaign-in-waiting. He labored through talking points, his plodding recitation occasionally drowned out by the BMWs and bicyclists whirring by in morning traffic. After about a minute, his answers began to curdle into a quasi-candid airing of grievances about the political process. He scolded the press for their hyperbolic campaign coverage ("I don't even read the clips"); dismissed the up-and-down nature of the primary polls ("It doesn't really matter"); and pleaded for patience and perspective in the early state-of-the-race punditry ("It's June, for crying out loud!").

Then, as though suddenly remembering himself, the almost-candidate abandoned candor and returned to script. "It's a lot of work, and I'm excited about the prospects of this," Bush said, conveying roughly the same excitement of someone expecting gallbladder surgery. "It's a long haul."

From the beginning, Bush has insisted his decision about whether to undertake a presidential run in 2016 would depend on his answer to one question: "Can I do it joyfully?" But now, as he officially launches his campaign at a Monday afternoon rally in Miami, Bush's pursuit of the presidency seems destined to be a grinding, grumpy ordeal — permeated with disdain for the trivial demands of campaign pageantry, and rooted in a sense of duty to save the GOP from a field of candidates he seems to regard as unprepared or unserious.

Joylessness wafts off Bush wherever he goes, from the photo ops on his just-completed tour of Europe to the grip-and-grins on the campaign trail in New Hampshire.

He responds with impatient sarcasm when he is forced to field questions about political strategy — or his brother's polarizing record — instead of public policy. "Anybody have some questions about Germany?" he deadpanned in Berlin, by way of announcing he was through talking about campaign personnel.

His strict adherence to the trendy, low-carb Paleo diet — with its onslaught of grilled chicken and raw almonds — has left him trimmer, crankier, and frequently complaining that he is hungry.

He has been told he needs to make an effort to smile more.

Of course, presidential campaigns have never been uniformly joyful affairs, and every candidate has their fair share of miserable days. But in Bush's case, the surface-level signs of weariness may be symptomatic of the fundamental rationale for his candidacy. Despite his long-held passion for public policy and stated desire to "develop a message that's hopeful and optimistic about the future of the country," Bush is not entering the Republican civil war as a true believer fighting zealously for one ideological tribe of conservatism. He is casting himself, instead, as the mature, sensible, electable candidate — the GOP grown-up with a proven ability to "move the dial" on key issues while in office.

This approach is premised on the belief that too many of his rivals are either inexperienced lightweights or aspiring celebrities auditioning not for the presidency, but for radio shows and book contracts. When he says that the Republican nominee must be willing to "lose the primary to win the general," he is not just defending his own violations of conservative orthodoxy on issues like immigration and Common Core education standards. He is also implicitly accusing his rivals of un-presidential pandering.

"I'm not going to change my views because today someone has a view that's different," he told reporters in Estonia. “I think candidates have a duty to persuade; that’s what this is about — it’s about the power of ideas and then giving people a sense that you have leadership skills to actually make it so."

The fundamentally oppositional nature of Bush's campaign is illustrated by his decision last week to swap out his perennially cheerful campaign manager, David Kochel, for the younger, more sharp-elbowed Danny Diaz, a master of rapid response and opposition research whom Bush touted as a "grinder." His campaign is now reportedly planning to use its well-stocked war chest to launch an aggressive assault this summer aimed at knocking off the other top-tier candidates in the field.