But in ways big and small, deliberate or subconscious, the younger Bush seems to have defined himself as the anti-George W. Bush: an intellectual in search of new ideas, a serial consulter of outsiders who relishes animated debate and a manager who eagerly burrows into the bureaucratic details.
Allies said that reputation - as what the Republican strategist Karl Rove called the "deepest thinker on our side" - could prove vital in selling Bush as a presidential candidate to an electorate still scarred by his brother's legacy of costly wars abroad and economic meltdown at home.
But the bookishness and pragmatism that strike mainstream Republican leaders as virtues highlight the potential difficulty that Bush may face in igniting the passions of more conservative members of the party.
The questions he grapples with most frequently, and enthusiastically, revolve around improving the effectiveness of government, in areas like education, immigration and criminal justice. It is a message unlikely to electrify Tea Party and libertarian wings of his party that are openly hostile to the very idea of government.
"There is skepticism that maybe Jeb Bush wants too much government in people's lives," said Greg Mueller, a Republican strategist who has advised the presidential campaigns of Pat Buchanan, Steve Forbes and Bob Dole. "I don't know that he will ever win over the limited-government conservatives."
Bush, who has cast himself as a party reformer, seems unfazed by such critiques: At times, he has appeared to deliberately fan them by publicly castigating the leaders of his own party for adhering to failed tactics and outdated messages.
After Mitt Romney's resounding defeat in 2012, in a presidential campaign that struggled to leaven its harsh tone with an optimistic vision for governing, Bush was unsparing, warning that the Republican brand risked becoming a millstone, "associated with being anti-everything." Much of the electorate, he said, believes that "Republicans are anti-immigrant, anti-woman, anti-science, anti-gay, anti-worker."
Those who have hashed over policy and politics with Bush describe him as a conservative animated less by rigid ideology than a technocrat's quest to identify which solutions work best.
"He's not interested in proving some sort of conservative point that less government is better, though he might believe that," said Philip K. Howard, the author of influential books about law and government, who has spoken frequently with Bush. "In all of my dealings with him, he's interested in how you make government deliver effectively. What are the incentives? How do you hold people accountable?" He added: "These are the discussions, frankly, that you want government leaders to have."
Friends and former aides have variously described him as a "policy wonk," an "ideas junkie" and, as Arthur C. Brooks, the president of the American Enterprise Institute, called him, "a top-drawer intellect."
It is a cerebral image that Bush readily and conspicuously embraces, inviting inevitable - and not always flattering - comparisons with his brother. (While George W. Bush, 67, left Yale with gentleman's C's after four years, Jeb Bush raced through the University of Texas in 2 1/2, graduating Phi Beta Kappa.) He insisted, for example, that his official portrait as governor contain a bookcase filled with his most beloved titles, among them "Cross Creek," a memoir by Marjorie Kinnan Rawlings.
These days, the younger Bush peppers his speeches with statistics, academic-sounding references to "quintiles" and self-deprecating jokes about his own geekiness. A few weeks ago, he boasted to a crowd of Republican donors that he was "nerdy enough" to read City Journal, an obscure policy magazine published by the Manhattan Institute, a conservative think tank, then recited the names of his favorite writers at the publication.
Aubrey Jewett, who has studied Jeb Bush as a professor of political science at the University of Central Florida, said he "seems to go out of his way to make it clear that he's different from his brother, by the way he talks about himself, his goals and the details of public policy."
And how he governed. Under Bush, who served from 1999 to 2007, the Florida governor's office at times resembled a mini-university. New employees showed up to find a copy of a treasured Bush book on their desks: "A Message to Garcia," the inspirational 1899 essay about a U.S. soldier who journeyed to Cuba to win the alliance of a rebel leader.