Updated

The Obama administration announced Thursday that it would launch a case-by-case review of illegal immigrants slated for deportation, in a move that could grant a reprieve to so-called DREAM Act beneficiaries and thousands of others.

The DREAM Act is a proposal in Congress to give illegal immigrants who came to the U.S. as children a chance at legal status if they complete two years of college or military service. Though the bill has not passed, supporters and critics alike suggested Thursday's announcement could serve to unilaterally carry out its provisions.

A spokeswoman with the Federation for American Immigration Reform described the new policy as "blanket amnesty."

But Homeland Security Secretary Janet Napolitano said in a letter to Senate Democrats that it would "enhance public safety" by focusing deportation efforts on those "who pose a threat."

Under the plan, DHS and the Department of Justice will review all cases in removal proceedings as well as any new cases to make sure those who are deported meet the kind of criteria established in a June 17 agency memo.

The memo from Immigration and Customs Enforcement Director John Morton instructed staff to consider 19 factors when exercising "prosecutorial discretion" -- or the discretion an ICE attorney has in deciding whether and how to pursue an immigration case. The list includes factors similar to those in the DREAM Act, like whether someone arrived in the U.S. as a "young child," is pursuing an education or has served in the military.

Thursday's announcement goes beyond the memo by establishing a process to flag and exempt certain illegal immigrants from deportation. A team of attorneys and officials will be tasked with reviewing the more than 300,000 cases in the system.

An ICE memo obtained by FoxNews.com said the effort would not provide "categorical relief for any group," but would try to prevent "low-priority" cases -- like those not involving convicted criminals -- from clogging the system.

Cecilia Munoz, White House director of intergovernmental affairs, wrote on the White House blog that the review would "clear out low-priority cases on a case-by-case basis and make more room to deport people who have been convicted of crimes or pose a security risk" -- while ensuring the low-priority cases are kept "out of the deportation pipeline in the first place."

Describing groups of people similar to those targeted in the DREAM Act, she said the low-priority list would include "individuals such as young people who were brought to this country as small children, and who know no other home," as well as "individuals such as military veterans and the spouses of active-duty military personnel."

She said that with more than 10 million people in the country illegally, the strategy is meant to focus limited resources on those who pose the greatest risk.

House Democratic Leader Nancy Pelosi and Senate Democratic Leader Harry Reid praised the decision.

"This new DHS directive will help prioritize our limited enforcement resources to focus on serious felons, gang members and individuals who are a national security threat rather than college students and veterans who have risked their lives for our country," Reid said in a statement. "I am especially pleased about the impact these new policies will have on those who would benefit from the DREAM Act. ... We lose a lot by sending them back to countries they do not know."

Reid said Congress should still pass immigration reform legislation.

Napolitano also stressed in her letter that the new process "will not alleviate the need for passage of the DREAM Act or for larger reforms."

But FAIR described the announcement as a complete overhaul of immigration law without approval by Congress.

"Having failed in the legislative process, the Obama administration has simply decided to usurp Congress's constitutional authority and implement an amnesty program for millions of illegal aliens," FAIR President Dan Stein said. "This step by the White House amounts to a complete abrogation of the president's duty to enforce the laws of the land and a huge breach of the public trust. ... In essence, the administration has declared that U.S. immigration is now virtually unlimited to anyone willing to try to enter -- and only those who commit violent felonies after arrival are subject to enforcement."