Senior US Republicans have set the Obama administration a deadline of December 13 to make public information about its refugee resettlement deal with the Turnbull government, in the latest threat to the plan before Donald Trump's inauguration as president.
New concerns from members of Congress came as Liberal backbench MP Craig Kelly cast doubt on the plan's viability on Wednesday, conceding it wasn't "a done deal" and suggesting Immigration Minister Peter Dutton should be developing a contingency plan.
The chairmen of the powerful House and Senate Judiciary Committees in Washington, Congressman Bob Goodlatte and Senator Chuck Grassley, restated their calls for the Obama administration to declassify information about the one-off plan signed with Australia last month, objecting to secret negotiations, which they said had "left Americans in the dark".
Previously, the pair said many of the 1800 refugees and asylum seekers being considered for resettlement came "from countries of national security concern" and some designated by the US State Department as state sponsors of terrorism.
They called on Department of Homeland Security Secretary Jeh Johnson and Secretary of State John Kerry to provide Congress with a briefing to review the classified agreement and said the American people should be given access to its terms.
"It is now absolutely apparent to us that there was no reason for the agreement to be classified from the outset, and that it should not continue to be classified," the pair wrote.
"The American people have a right to be fully aware of the actions of their government regarding foreign nationals who may be admitted to the United States.
"American taxpayers not only foot the bill for the majority of the refugee resettlement in the United States, but they bear any consequences regarding the security implications of those admitted to the US."
Fairfax Media understands the State Department is preparing to respond to the letter directly, while staff on the two committees have received classified and unclassified briefings about the plans.
Mr Trump called for a moratorium on Muslim immigration to the US during the election campaign.
The Republicans will control Congress and the White House after January 20, raising the prospect of the Australia-US deal being overturned before any transfers take place.
Mr Kelly was critical of refugees being held in Australian detention who have said they are unwilling to go to the US.
"It's not a done deal until the people from Nauru go to the USA but one of the issues . . . is some of the people on Nauru say they don't want to go to the USA," he told Sky News.
"They're given an opportunity people would kill for, a Green Card to the USA, and they're rejecting it."
Mr Kelly said the government was preparing contingency plans in case the deal was scrapped.
"I am sure Peter Dutton is looking at a plan B as we speak. Plan A is to offer places in the USA, [a] fantastic opportunity for people to get themselves off Nauru.
"Obviously ministers are working on a plan B in case it falls over."
A spokeswoman for Mr Dutton said had "made it clear they are not going to be providing a running commentary on these matters."
Mr Dutton said in November the government would not provide any specifics about the deal and wouldn't comment on any negotiations Australia might be having with other countries.
