White House spokesman Scott McClellan said a policy review could allow some former members of Saddam's Baath party to join an interim Iraqi government being put together by the United Nations.
Around 400,000 people were thrown out of work last May when US administrator Paul Bremer dissolved the armed forces, security services and defence and information ministries. An appeals system was set up to allow them to reclaim jobs.
"The appeals process sometimes has been slower in implementation than was originally designed," US spokesman Dan Senor told a Baghdad news conference.
Those who were Baath Party members in name only would be welcomed, spokesmen said, but those tainted by their role in Saddam's "brutal" regime before it was toppled a year ago would remain excluded.
The top echelons of the Baath Party were drawn mainly from Iraq's Sunni Muslim minority to which Saddam himself belonged.
Resistance fighters in Sunni heartlands north and west of Baghdad have put up the stiffest resistance to the US-led occupation, partly because the community has felt penalised and excluded from power since Saddam's fall.
While President George Bush has touted the planned 30 June sovereignty handover in Iraq as a landmark, congressional Democrats on Thursday questioned whether it in effect would be just another day in the US-led occupation.
Administration plans for a "super embassy" and the continued presence of some 135,000 US troops mean Iraqis will see little change after the transfer, several lawmakers said.
They said Bush risked raising false expectations that could backfire in another surge of violence.
But Under Secretary of State Marc Grossman told the Senate Foreign Relations Committee, "My message today ... is on the first of July Iraqis will be in charge of Iraq, Iraqis will run Iraq."
US House of Representatives Minority Leader Nancy Pelosi told reporters the Bush administration was trying to create an "illusion ... that there will be a transfer to a sovereign government of Iraq".
Pelosi, a California Democrat, said she thought the White House was not showing "too much angst as to what the nature of the Iraqi government will be, starting June 30" because it is essentially a handover of authority from the US-led occupation to the new US embassy there.