President Obama has said that illegal immigrants who entered the US as children will no longer be deported and may instead get two-year work permits.
The move is seen as aimed at Hispanics whose votes could be crucial in an election year.
It affects immigrants aged under-30 who have lived in the States for five years.
“Now, let’s be clear: This is not amnesty. This is a temporary stop-gap measure that lets us focus our resources wisely while giving a degree of relief and hope to talented, driven, patriotic young people. It is the right thing to do,” Obama told reporters at the White House.
The president was surprised to be heckled by a reporter from a conservative publication. Neil Munro from the Daily Caller was among the audience on the lawn, and interrupted Obama’s statement.
The president replied:
“The answer to your question sir, and the next time I prefer you let me finish my statements before you ask that question, is this is the right thing to do for the American people.”
Then, as Obama left, a voice called out: “What about American workers who are unemployed while you employ foreigners?”
Hispanic groups have criticised Obama’s administration for deporting hundreds of thousands of illegal immigrants.
Many young immigrants brought into the US illegally by their parents have become integrated into American society and have few ties with their countries of origin.
But many Republicans are against loosening immigration rules. The change of policy has been attacked by Obama’s Republican opponent, Mitt Romney.
He said it would make it harder to reach a long-term solution for young illegal immigrants, and the issue should be dealt with by Congress not executive order.