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The Department of Homeland Security on Friday denied any plans to grant blanket amnesty to the "entire illegal immigrant population," following claims from senators and others that the Obama administration has been holding behind-the-scenes talks to craft a gameplan for mass legalization.

The concern is that DHS, in a bid to bypass Congress, would extend what is known as deferred action or parole -- actions usually taken on a case-by-case basis -- to millions of illegal immigrants at once.

The department statement, however, did not address the possibility of giving a selective reprieve to the segment of the population holding expired visas -- as opposed to those who crossed illegally. This is something that a former Bush administration official told FoxNews.com could be an option.

But the statement said the reprieves would not be drastically expanded. The department, while affirming its authority to grant the extensions "on the merits of cases," said they are applied on a "case-by-case" basis.

"DHS does not grant deferred action without a review of relevant facts," the statement said. "To be clear, DHS will not grant deferred action to the nation's entire illegal immigrant population."

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The Department of Homeland Security expressed the administration's support for the recently unveiled Senate immigration overhaul, calling it "a step in the right direction."

But several sources said it was their understanding that the administration has been discussing alternatives to congressional action.

Rep. Steve King, R-Iowa, said he's spoken with people contacted by the White House for their opinion on ways to provide "amnesty for a large number of people."

The congressman said the administration is either considering the option or floating it as a trial balloon for "leverage" to pass the immigration bill.

"It's one or it's the other," he said.

In a separate interview, a former Bush official claimed to have spoken with at least people involved in the administration talks on the subject and said at the minimum, the administration was "studying legal ways to legalize people without having to go through any congressional debate about it."

The former official said targeting the segment of the population that had overstayed visas could work, though such a plan would be "woefully inappropriate."

The Department of Homeland Security estimated last year that 10.8 million undocumented residents live in the United States -- the Pew Hispanic Center, which has a similar count, estimated in 2006 that at least 4 million of them overstayed their visas.

The issue was raised publicly earlier this week by eight Republican senators who wrote to the White House complaining that they had heard the administration was readying a "Plan B" in case a comprehensive immigration reform bill cannot win enough support to clear Congress.

They warned that any unilateral action would "further erode the American public's confidence in the federal government and its commitment to securing the borders and enforcing the laws already on the books."