Denver ? In a trial of a politically divisive program, U.S. prosecutors in Denver and Baltimore are reviewing thousands of deportation cases to determine which illegal immigrants might stay in the country — perhaps indefinitely — so officials can reduce an overwhelming backlog by focusing mainly on detainees with criminal backgrounds or who are deemed threats to national security.

Federal deportation hearings for noncriminal defendants released from custody were suspended Dec. 5 for the review and resume this week. Similar reviews are planned across the country to allow U.S. Immigration and Customs Enforcement to target deportations of illegal immigrants with criminal records or those who have been deported previously.

While the immigration courtrooms in Denver have fallen silent, prosecutors had time to examine case files, check residency history, such as whether someone was brought to the country as a child, as well as criminal history.

In Denver, 25 ICE prosecutors and three managers spent their work days during most of December and early this month poring over as many files in their case load as possible, ICE spokeswoman Barbara Gonzalez said.

“They come in on weekends,” Gonzalez said. “They’re looking at every case.”

Officials have not released information on how many cases will be placed on low priority based on the review. When they’re finished, cases of those here illegally but deemed not a threat to public safety or national security will be placed on administrative hold and the numbers will be released.

Citing tight budgets, Homeland Security Secretary Janet Napolitano announced this summer that nearly 300,000 deportation cases would be reviewed to determine which could be closed through “prosecutorial discretion.” Republicans have decried the policy as a back-door way of granting amnesty to people who are living in the U.S. illegally.

“We simply cannot adjudicate all these cases that are pending,” said spokeswoman Gonzalez. Some cases in Denver date to 1996, she said.

“It’s a holiday for anybody in the country illegally,” said Ira Mehlman, spokesman for the Washington-based Federation for American Immigration Reform, which opposes the initiative. “They’re doing this with the intention of dismissing as many of them as they possibly can.”