UPDATE: Since it was first reported, figures for the investigation have been revised downward. The Post updated its story to say two law enforcement officials said the figure is too high. The FBI would not provide the paper an exact figure, but the officials said the number of FBI personnel involved is fewer than 50.

The Washington Post reports that the large number of agents have been deployed to run down leads in the investigation, citing a lawmaker briefed by FBI Director James Comey.

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The Post reported that the FBI has accelerated its investigation because officials want to avoid potentially announcing any action close to the November election.

Comey has signaled that he is personally close to the probe into Clinton's personal email account used during her time as secretary of State.

“What I can assure you is that I am very close personally to that investigation to ensure that we have the resources we need, including people and technology, and that it's done the way the FBI tries to do all of it's work: independently, competently and promptly,” Comey told lawmakers in early March.

Federal investigators are working to establish whether any laws were broken with the handling of classified material. Clinton's campaign has pushed back on what it views as over-classification of the emails, many of which were retroactively classified.

Clinton has also said the law allowed her to use a personal email server, though she has acknowledged an error in judgment.

The issue had been a thorn in the side of Clinton’s presidential campaign and is likely to be a major issue in a general election fight.

The FBI and prosecutors investigating Clinton's private server have begun the process of setting up formal interviews of longtime aides, according to the Los Angeles Times, which reported that the process could help investigators better understand whether classified material was knowingly or negligently discussed over the non-secure email system.

— The post was updated on March 31 at 5:33 p.m.