Jeb Bush once called for building prisons and emphasizing "punishment over therapy" for juvenile offenders. Today, he supports reforming the criminal justice system, arguing that incarceration can harden low-level lawbreakers into career criminals.

In the past, he stressed using deportation to rid the United States of unauthorized immigrants. These days, he describes crossing the border illegally as "an act of love" by migrant parents and supports a path to citizenship for those who have done so.

He used to emphasize the rights of big landowners who felt cheated by environmental programs. Now, he is a champion of state-sponsored conservation, celebrated for his $2 billion program to restore the Everglades.

Bush, 61, the former governor of Florida, insists that he will not contort himself to satisfy the ideologues of the Republican Party as he lays the groundwork for a possible presidential run in 2016. But as he pledges to stay true to his beliefs, an examination of Bush’s record reveals ways in which those views have already changed since his first run for elected office – in presentation, in tone, in language and, at times, in substance.

The long trail of Bush’s pronouncements – from his days as a candidate for governor of Florida in 1994 to today in his role as a public policy expert bent on recasting the Republican brand – will inevitability invite suspicion from within his party that he lacks genuine conservative conviction, a wariness that he needs to overcome to win the Republican nomination. But the journey may give Bush the broader, cross-party appeal necessary to compete in a presidential general election.

Over the past two decades, Bush has shifted from a doctrinaire and, in his word, "headbanging" version of conservatism, forged in the crucible of Newt Gingrich’s revolt-driven Republican Party, to a more nuanced approach – one influenced, colleagues said, by his immersion in the multiculturalism of Florida and his adoption of the Catholic faith.

"There is an evolution in temperament and an evolution in judgment and an evolution in wisdom – and there is an evolution in his respect for others’ point of view," said Al Cardenas, a longtime friend who insisted that Bush had "not changed his conservative values."

Policy adjustments big and small are routine in American politics. Mitt Romney, the former governor of Massachusetts, and Gov. Chris Christie of New Jersey once supported abortion rights. Now both oppose them. President Barack Obama and Hillary Rodham Clinton, a likely presidential contender in 2016, previously objected to same-sex marriage; today, they support it. In each case, cultural change seemed to alter personal beliefs to political advantage.

For Bush, the pattern was illustrated last week by a head-turning statement on the legalization of same-sex marriage in Florida, when he urged "respect" for the unions and offered words of conciliation to same-sex couples "making lifetime commitments to each other."

In 1994, as he ran for governor in Florida, Bush employed strikingly different language when discussing gay rights, arguing that "polluters, pedophiles, pornographers, drunk drivers and developers without permits receive – and deserve – precious little representation or defense from their governor." He concluded that "we have enough special categories, enough victims."

From that point, he has been on a long walk away from such harshness. Friends, advisers and outside analysts said the deepest transformation had occurred after his loss in the 1994 race, even as the Republican Party achieved victories so sweeping that it took control of the House of Representatives for the first time in 40 years.

His unstinting message of financial austerity and tear-it-down conservatism had alienated many Florida voters.

"He lost because he did not come across as particularly likable," said Aubrey Jewett, a professor of political science at the University of Central Florida who has studied Bush. "He was harsh."

Sally Bradshaw, who advised Bush during that period, said: "He learned from his loss that there are ways to bring people together and ways to drive people apart. The lesson from ’94 was that he wanted to bring people together."

A chastened Bush re-evaluated his style. He co-founded a charter school in an impoverished Miami neighborhood and visited shelters for abused women. He played down rigidity.

"The ideological battle is not as important as it once was," he told The New York Times in 1998 as he prepared his second race for governor, which he won.

A useful case study: the environment. Before the 1994 election, Bush supported a state constitutional amendment, also backed by big corporations, to compensate landowners hurt by conservation efforts. He held out the prospect of cutting funds for a major program to purchase environmentally fragile lands and declared that "excessive regulation does not mean we are going to improve the quality of water, air or land-use planning."

Allison DeFoor, who was a top environmental adviser to Bush when he became governor, said bluntly, "He was hostile to the environment in 1994."

But Bush was open to arguments from the other side. He met with conservation experts and toured important environmental sites across Florida. When he was elected four years later, "his heart changed," DeFoor said.

As governor, Bush invested heavily in a plan to restore the Everglades, eroded over time by development and agriculture. He called the wetlands "a treasure" and kept a toy version of a manatee, an endangered aquatic mammal, on his desk.

Bush "does not flip-flop," DeFoor said. "He learns. When he learns, he changes."

Bush, a former real estate developer, was particularly influenced by the experience of governing, aides said. Once elected in 1998, he suddenly had access to measurements of what worked, and what did not, on issues like juvenile justice.

At times, though, the winds of political change have appeared to quickly upend Bush’s thinking. In 2012, he wrote the book "Immigration Wars," in which he opposed a direct pathway to citizenship for immigrants in the country illegally. He called it "an undeserving reward for conduct we cannot afford to encourage."

By the time the book was published in 2013, the Senate was preparing to pass bipartisan legislation that included such a pathway. Bush, when pressed in interviews, backed away from his resolute position, saying he could support citizenship.

In other cases, Bush has simply changed the way he talks about an issue. On same-sex marriage, he has not embraced legalization, yet he has adopted sympathetic, accepting language.

Matthew T. Corrigan, a professor at the University of North Florida who wrote a book, "Conservative Hurricane," about Bush’s agenda as governor, said Bush’s "overall presentation has changed, especially since he left the governor’s office" in 2007.

The modifications, he said, are more opportunistic than ideological.

"He saw that the Republican Party looked anti-everything and needed a bigger tent," Corrigan said. "His approach to explaining issues and talking about politics has adapted to that."

Bush hinted at this during the last Republican presidential primary when, dismayed by intraparty squabbling, he warned the candidates.

"You have to maintain your principles," he said, "but have a broader appeal."

Michael Barbaro, New York Times