A federal judge in Manhattan will decide, as early as tomorrow, whether to force the federal government to process a backlog of tens of thousands of citizenship applications in time for Election Day.

The backlog is partly attributable to a spike in applications last year prompted by an announcement of fee increases. It is also due to a bottleneck in the naturalization process related to FBI reviews of its investigative files for adverse information about applicants. Such reviews — which were made more comprehensive after it was discovered that the federal government in 2002 had naturalized a person with ties to Hezbollah — are at the heart of a class action in Manhattan on behalf of as many as 55,000 immigrants in the New York region who have citizenship applications that have been pending for more than half a year.

The judge, Lawrence McKenna of U.S. District Court in Manhattan, is expected to issue a ruling tomorrow, two people familiar with the case said. The plaintiffs are asking him to force the U.S. Citizenship and Immigration Services to adjudicate citizenship applications “without waiting for the results” of the FBI checks, which are known as “name checks,” according to court papers filed by the Puerto Rican Legal Defense and Education Fund. Waits endured by applicants can take several years.

In court papers, a government attorney, Robert Yalen, wrote bluntly: The “FBI does not owe any duties to individuals whose name it is running.” Still, court exhibits the government has submitted indicate that it is taking steps to clear the 350,000 name checks remaining as of March, including the hiring of contractors.

In two-thirds of cases, the FBI is able to conduct a name check and respond to immigration officials in less than three days, according to a court brief submitted by Mr. Yalen. In about 17% of the cases, waits of at least two months — and potentially much longer — occurred due to the need to track down paper files in a distant field office or the need to find an FBI agent with knowledge of a particular case, Mr. Yalen’s brief said.

Until 2002 or more recently, the FBI’s background check for would-be citizens only flagged files that were primarily devoted to the would-be citizen, Mr. Yalen wrote. The FBI subsequently began checking names of would-be citizens against a database that includes suspects, victims, and witnesses to a crime, as well as any persons considered pertinent to an investigation in any way.

The identity of the naturalized person with links to Hezbollah has never been publicly identified.