The backlog has led to major processing delays and disrupted thousands of Americans' summer travel plans.
Three groups of 150 employees have been removed from their current posts in Washington and told Tuesday to report for two months of duty at passport facilities in Louisiana and New Hampshire as the department struggles to cope with overwhelming demand, officials said.
Those with pressing family commitments in the Washington area will be allowed to work at the passport production agency here.
Secretary of State Condoleezza Rice and her deputy, John Negroponte, ordered the step because already drastic steps taken to reduce the backlog of millions of applications were not working fast enough, said Patrick Kennedy, the department's management policy chief.
"The secretary and deputy secretary asked us to mobilize enough people to meet the demand and this is what we did," he said.
Those chosen for the duty already have the necessary security clearances to process the applications but will undergo a week-long refresher course beginning July 9. Many will arrive in New Orleans, La., and Portsmouth, N.H., the following week for the stints that end in August.
The State Department is paying travel and accomodation expenses plus a per diem allowance for meals and for one long weekend break over the two months, though some have grumbled about their assignments.
But Kennedy and other officials noted that both foreign and civil servants are required by law to accept temporary assignments that involve relocation. Most of those selected have been working for the State Department for fewer than five years, they said.
The "mobilization" is just the latest in a series of measures the State Department has taken to deal with the crisis, which has prompted millions of furious complaints from U.S. citizens and calls for investigations from irate lawmakers.
Last month, the department issued an urgent all-points global appeal for volunteers from U.S. embassies and consulates abroad to return to the United States for the summer to clear the backlog of almost 3 million applications and thousands more that pour in each day. The department says the wait for a new passport is now as long as three months, up from only six to eight weeks.
The problem reflects a massive rush for passports by Americans because of post-Sept. 11, 2001, security upgrades that took effect in January requiring them to present passports when returning by air to the United States from Canada, Mexico, the Caribbean and Bermuda.
Under heavy congressional pressure, that requirement was suspended until the end of September as long as travelers can show proof their passport applications are pending.