The Democratic chairwoman of the Senate Intelligence committee commissioned a federal report to identify prison facilities in the U.S. that are suitable for housing Guantanamo detainees, concluding the option is viable -- despite congressional opposition to such a plan when the Obama administration proposed it.

Sen. Dianne Feinstein's renewed interest in the proposal first came to light Wednesday after Fox News turned up an internal Government Accountability Office document that refers to “Source of Work: Ms. Dianne Feinstein, Chair, Select Committee on Intelligence, U.S. Senate” and lists the “Gist of Work” as an investigation into whether domestic facilities could house the approximately 170 detainees remaining at the controversial facility in Guantanamo Bay, Cuba.

Two hours after Fox News' inquiry about the report, Feinstein's office posted the report online and released a statement confirming that the California senator thinks the Obama administration's controversial plan to relocate detainees to the United States is a viable option.

“This report demonstrates that if the political will exists, we could finally close Guantanamo without imperiling our national security,” Feinstein said. “The GAO report makes clear that numerous prisons exist inside the United States -- operated by both the Department of Defense and the Department of Justice—capable of holding the 166 detainees who remain at Guantanamo in an environment that meets the security requirements.”

Past discussion of moving the detainees stateside sparked a firewall of bipartisan opposition in Congress, which passed a measure barring that move.

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The internal GAO document reviewed by Fox News noted the president’s executive order of January 2009, in which he promised to close the detention camps there within a year, and it referenced “legal prohibitions” that currently bar the transfer of detainees to the U.S. But the document also stated that Congress has continued to raise questions about whether civilian or military facilities in the United Sates could house the men.

“To address this, GAO is providing information on the current characteristic of the detention facilities at Guantanamo Bay, as well as descriptions of existing DOD (Defense Department), Department of Justice, and Department of Homeland Security correctional and detention facilities," it says.

The GAO's report on the facilities, which was completed Nov. 14, included four objectives: an analysis of the current Guantanamo Bay detention camps, examination of the extent Defense Department and civilian facilities could be used, an outline of how the Justice and Homeland Security departments manage individuals who “engage in terrorist-related activities” and an overview of the challenges of housing detainees in the U.S.

Congressional sources tell Fox News that Feinstein, a California Democrat, placed a 30-day hold on the report, which has the effect of limiting access to the report’s findings until its public release. Until that time, sources say, Feinstein can share the findings with whom she chooses. However her office disputed that characterization, saying that it is standard for the GAO to delay public release of one of its reports until after the requestor has reviewed it.

Republican Rep. Frank Wolf of Virginia, who heads the powerful subcommittee on appropriations overseeing the Justice Department, said he thinks the department's acquisition last year of a prison in Illinois was “unprecedented in its violations of longstanding executive-legislative branch protocol."

It "could be the first step in transferring the world’s most dangerous terrorists from Guantanamo Bay to the U.S.,” Wolf said.

“Senator Feinstein’s request for this GAO report raises even more suspicion about plans by the Obama administration to transfer Guantanamo detainees to U.S. prisons, and even more troubling is the fact that the report’s findings were kept secret from the Congress and the American public,” Wolf said.