US President Barack Obama has said he will take action to reform immigration this year.
Mr Obama blamed Congress for failing to act and said he would try to make the system work better.His remarks follow reports in the New York Times and Fox News that he plans to extend protection from deportation to some parents of legal US residents.
The overall plan is estimated to affect as many as five million undocumented immigrants living in the US.
Republicans in Congress say such action would be beyond Mr Obama's authority.
'Tooth and nail' At a news conference in Yangon with Myanmar opposition leader Aung San Suu Kyi, Mr Obama said he had given the House of Representatives more than a year to come up with an immigration bill but they had failed to do so.
"I said that if in fact Congress failed to act I would use all the lawful authority I possess to try to make the system work better," he said.
"And that's going to happen before the end of the year."
Mr Obama added that as soon as Congress passed a bill he could sign, "any executive actions will be replaced".
"We're going to fight the president tooth and nail if he continues down this path," House Speaker John Boehner told reporters.
Mitch McConnell, the incoming Senate majority leader, urged the president to "work with us to try to find a way to improve our immigration system".
The BBC travelled to California and Mexico, to report on US deportees
Some Republicans are pushing for the budget bill to include a statement prohibiting "the use of appropriated funds for the president's immigration machinations".
Such a move could provoke a block by the Democrats, or a veto by the president, which in turn raises the risk of a government shutdown.
At the centre of the reports is a plan to extend the president's "deferred action" plan, which was designed to protect young adults who were brought to the US illegally as children from being deported.
The plan is to extend that to the parents of children who are US citizens or legal residents.
The action is designed to prevent the break-up of families via deportations. The number of those affected by the suggested policy is based on how long an individual has lived in the US.
If the administration limits the "deferred action" to those who have lived in the US for more than 10 years, it would affect 2.5 million undocumented immigrants, experts estimate.
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Other parts of the executive action reported by the media include:
- increasing the number of high-tech workers allowed to live and work in the US
- an expansion of the existing deferred action plans that would move the cut-off date for children arriving to 2010
- shift border security resources to the US southern border, according to reports.