Immigrants who applied for U.S. citizenship after June 1 will have to wait more than a year to become Americans, immigration officials said — a delay that will prevent many from voting in next November's presidential elections.

The delay is due to a deluge of applications that Citizenship and Immigration Services, a Homeland Security Department agency, received this summer as immigrants rushed to beat drastic fee increases for naturalization, legal residency, work permits, international adoptions and a number of other immigration benefits.

That means naturalization applications filed after June 1 will take 15 months to 18 months to process and become final, said Bill Wright, spokesman for the immigration agency.

"We certainly are hoping to beat that, but there certainly is that possibility," Wright said. Generally, becoming a citizen takes on average about seven months after an application has been filed, Wright said.

A total of 2.5 million applications were filed with the agency during July and August, Wright said. He could not provide numbers for June.

For the fiscal year that ended Sept. 30, a total of 7.7 million applications were filed, compared with 6.3 million the previous fiscal year, Wright said.

The spike in applications came in the months before Citizenship and Immigration Services raised all application fees, effective July 30. Costs for applying for citizenship rose from $330 to $595 (euro401) and from $325 to $930 (euro627) for legal residency. In both cases, applicants also must pay fingerprinting fees, which increased from $70 to $80 (euro54).

The wait for naturalizations could hurt efforts of a coalition of groups trying to increase citizenship and voter registration among immigrants.

The delays have raised some concerns about possible political motivations, which Wright denied.

"I would hope there's not a political motivation because citizenship is too valuable for partisan mischief," said Arturo Vargas, executive director of the National Association for Latino Elected and Appointed Officials, one of the groups leading the registration campaign. He said Congress should provide money to the agency to get the naturalizations done sooner.

In 2006, the largest number of immigrants who naturalized were from Mexico. Hispanics in the U.S. tend to vote Democratic, although some experts suggest many recent immigrants are less likely to have aligned themselves yet with either major party.

Strong opposition from Republicans to immigration overhaul bills this year and in 2006 angered many Hispanics. Last year, the immigration debates triggered massive protests in cities throughout the United States, where marchers chanted, "Today we march. Tomorrow we vote."

Wright maintained the agency would not sacrifice security to speed up processing applications.

The administration of former President Bill Clinton faced criticism for rushing to naturalize 1.2 million people in an 1996 attempt to cut massive backlogs. The Justice Department concluded thousands of those people did not receive adequate background checks, but determined the naturalization rush was not politically motivated.

A total 1.4 million people applied for naturalization in the 2007 fiscal year, about double the number from the previous fiscal year. Another 876,000 applied to become legal residents in fiscal year 2007, up from about 500,000.

The most naturalization applications, 562,423, came in July, August and September, up from 192,423 for the same three months in 2006.