But the measure is only a temporary fix, Soults said, because it is a policy dictated by the Obama administration. If the White House were to change hands, he said, young immigrants’ legal status would be in jeopardy. Pro-immigration advocates, he said, must still push for the passage of the DREAM Act, proposed legislation that provides a pathway to citizenship for young people who immigrated illegally.

Jessica Vaughan, director of policy studies at the Center for Immigration Studies, which prefers stricter controls on immigration, said this was a “risky political move” by Obama, whose rival in the presidential race is sure to attack him for it.

Obama has been a long-time supporter of the DREAM Act, which has stalled in Congress since the 1990s.

“This is a pretty blatant attempt to enact the policy by executive fiat,” she said. “This is clearly an end run around Congress and at odds with what most people want to see happen.” She said the policy change will probably help to legalize tens of thousands, possibly hundreds of thousands of young people.

Homeland Security Secretary Janet Napolitano outlined the new policy in a memorandum released today.

“Our nation’s immigration laws must be enforced in a strong and sensible manner,” Napolitano wrote. “They are not designed to be blindly enforced without consideration given to the individual circumstances of each case. Nor are they designed to remove productive young people to countries where they may not have lived or even speak the language.”

In the memorandum — addressed to top officials from US Customs and Border Protection, US Citizenship and Immigration Services, and US Immigration and Customs Enforcement — Napolitano outlined the criteria for people who qualify for the exemptions from deportation proceedings.