Former Florida governor Jeb Bush, one of the Republicans' leading hopes for the 2016 presidential election, was speedily backtracking Tuesday after throwing into confusion the party's stance on immigration reform, one of the key issues of Barack Obama's second term.

Bush, long a champion of immigration reform in the face of sustained Republican grassroots opposition, surprised his own party by adopting a more right-wing stance in a new book, Immigration Wars, published Tuesday. But within hours of publication, he changed his position again, reverting to his original, more progressive line.

Bush's about-turns come as the Obama administration is pushing for immigration reform that would create a path to citizenship for the estimated 11 million undocumented workers in the US, many of whom crossed the border illegally from Mexico.

The Republican party, having been badly punished by Latinos in the November White House election over its opposition to reform, has been shifting its position over the last four months. A bipartisan group in the Senate, that includes Republicans Marco Rubio, John McCain and Lindsey Graham, is due to publish proposals for a bill this month supporting a path to citizenship.

But Bush, in the book co-authored with constitutional lawyer Clint Bolick, puts himself at odds with the bill emerging from the Senate. Instead of a path to citizenship, he argues in favour of a path only to residency. Pro-immigration groups oppose the latter option, saying there would be little incentive for undocumented workers to come forward.

Interviewed on the Today programme on Monday ahead of publication, Bush said that rewarding "illegal immigrants" with citizenship would just encourage more to cross the border.

"I think there has to be some difference between people who come here legally and illegally. It is just a matter of common sense and a matter of the rule of law. If we're not going to apply the law fairly and consistently, we're going to have another wave of illegal immigrants coming into the country," he said.

But 24 hours later, after widespread surprise over his unexpected policy shift, Bush went on MSNBC to disavow the views in the book. He said he would support a path to citizenship for undocumented immigrants if a way could be found to produce legislation that would not act as magnet for more undocumented migrants.

"If you can craft that in law, where you can have a path to citizenship where there isn't an incentive for people to come illegally, I'm for it," he said. "I don't have a problem with it. I don't see you how you do it, but I'm not smart enough to figure out every aspect of a really complex law."

The book was supposed to be part of a campaign to position Bush, brother of George W Bush, as a potential future candidate for the Republican presidential nomination. He refused in an interview on Monday to rule out running in four years' time.

Instead of building a platform on which Bush could run, the book has damaged the reputation he built up as a popular and astute politician. The debacle has opened him up to accusations by opponents of being a flip-flopper, one of the charges against failed 2012 Republican candidate Mitt Romney.

One of Bush's main rivals for the Republican nomination is expected to be Rubio, the senator from Florida who is of Cuban descent and who is promoting a bill that would offer a path to citizenship.

There was no clear explanation Tuesday why Bush shifted to the right. One view is that he wanted to position himself to the right of Rubio. Another explanation was that Bush, who is married to a Mexican who became an American citizen, remains committed to reform and his move was simply tactical. According to this interpretation, he did not think when he handed the draft for publication before Christmas that the Republican party would stomach the prospect of a path to citizenship and did not anticipate the shift in mood that seems to have occurred.

Marshall Fitz, director of immigration policy at the Center for American Progress, said in the National Journal: "He sent the book to the printer at a time when he was anticipating the direction of the debate tilting against citizenship. It is clearly contrary to what he has said before. In hindsight, Americans have always judged severely efforts to deny citizenship to classes of people. Is this really the GOP's path out of the political wilderness?"

Immigration reform is one of the few areas in deeply divided Washington where there is scope for compromise, at least in the Senate. The proposed bill could still run into trouble from Republicans in the House who had been quiet on the issue and may be emboldened by Bush's opposition, albeit temporary, opposition to a path to citizenship.

The controversy is set to dog Bush. He is scheduled to speak at the libertarian thinktank the Cato Institute on Wednesday about immigration and is one of the key speakers at a major conservative conference in Washington, CPAC, later this month.