Republican leaders are abandoning their long-standing opposition to granting 11million illegal immigrants the right to stay in the US after Barack Obama's overwhelming victory among Hispanic voters in last week's election.
Remarks by John Boehner, the Speaker of the House, which appeared to break a major conservative taboo on immigration, set up a fierce debate within party rank and file, which is still reeling from the president's re-election last Tuesday.
Without giving specifics, Boehner said that "a comprehensive approach is long overdue". He added: "What I'm talking about is a common-sense, step-by-step approach to secure our borders, allow us to enforce the laws and fix a broken immigration system. It's just time to get the job done."
John Fleming, a Republican congressman from Louisiana, expressed concern that Boehner had not consulted colleagues before "making pledges on national news". But Boehner's comments raised hopes in Washington that one of the most divisive issues in the country could be resolved after years of bitter debate.
Senator Charles Schumer, the Democratic chairman of a Senate subcommittee on immigration and border security, called Boehner's comments a "breakthrough". In a sign that grassroots opposition to immigration reform may now change Sean Hannity, an influential conservative media commentator, said his views on the subject had "evolved".
Hannity, a Fox News and talk radio host, said he no longer believed that Hispanics who came to the US without paperwork should be kicked out if they are working, raising families and not committing crimes. Instead, he said, they should be offered "a pathway to citizenship", a phrase regarded on the Right as a euphemism for an amnesty for illegal immigrants.
An attempt by Obama to "fix our immigration system", promised in his victory speech last week after he won 71% of the Hispanic vote, is likely to be the biggest social issue he tackles in his second term. The president's immediate task, however, is to steer the country clear of the so-called fiscal cliff that would trigger $607billion of cuts and tax increases on January 1 if he and Congress cannot agree on solutions for controlling the deficit.
Numerous conservatives have said that the Republican party requires a period of examination about how to attract women and minorities.
Al Cardenas, the head of the American Conservative Union, said: "Our party needs to realise that it's too old and too white and too male, and it needs to figure out how to catch up with the demographics of the country before it's too late."