The application backlog is so large that Citizenship and Immigration Services, a division of the Homeland Security Department, is months behind schedule in returning receipts for checks written to cover fees - an early step in the process.
"Were we caught off guard by the volume? Let's just say it was anticipated it would increase. It was not anticipated it would increase by that much," said Emilio Gonzalez, director of Citizenship and Immigration Services.
The immigration agency would not say how many applications it has received. The American Immigration Lawyers Association, a private legal advocacy group, said it was told by agency officials that 3.5 million applications had come in over a two-month period. The agency projected a workload of 3.2 million applications for fiscal years 2008 and 2009.
Gonzalez ordered his staff to give priority to naturalizations, but some applicants will miss voting in primaries, which begin in January.
"I really want to target the elections," Gonzalez said. "I really want to get as many people out there to vote as possible."
The onslaught of applications has led to some files being sent back with errors or mistakenly rejected, while others seem lost in the system, applicants and attorneys say. Service centers in Nebraska and Texas have the longest delays. The Texas Service Center is working on applications dating from July 26, according to the agency's latest Web posting.
Boston janitor Betsy Camacho, 44, applied for U.S. citizenship on July 27. On Nov. 9, she got a receipt acknowledging the check she wrote for her fees had been deposited and her information was logged in the agency's computer.
Normally such receipts are returned to applicants within a week to 10 days, immigration attorneys said.
"I would like to vote, to participate, to travel with a passport, have freedom of expression," Camacho said. A native of El Salvador, she has lived in the United States for nearly 25 years.
Some groups that have been waging national campaign to help 1 million legal residents become citizens and vote in 2008 fear the pileup will hurt their efforts.
"Everybody keeps saying immigrants don't want to be part of this country, they don't want to assimilate and here people are coming in droves to show how much they want to be part of this country and here are these barriers. I think it's unconscionable," said Eliseo Medina, executive vice president of Service Employees International Union.
The application crush was worsened by another flood of about 300,000 applications from skilled workers wanting to become legal residents. The agency initially said it wouldn't accept the visa applications but changed its mind amid public outrage.