A leaked opposition file on Donald Trump has emerged - but the real file is probably much larger

Several hundred pages of a Democratic National Committee file of opposition research on Donald Trump is now public. But it's hardly the complete research brief that the organization is working on to thwart the presumptive GOP nominee from becoming president.

On Wednesday, Gawker published a leaked version of one of the DNC's early opposition files on Trump. It was written in December.

The 200-page playbook outlined attacks on Trump - including over his business record and inflammatory statements about female celebrities - but included what some observers noted was highly publicized information about the real-estate magnate that was easily searchable online.

Several sources familiar with the DNC's opposition research on Trump told Business Insider that the December files appear far more incomplete than the organization's current database of potential attacks.

One source familiar with the DNC's current opposition file on the real-estate mogul told Business Insider that the December document was presented by just a handful of staffers assigned to looking into Trump's most obvious controversial statements from his past.

As it became increasingly apparent that Trump would become the nominee, the committee diverted dozens of staffers toward compiling and farming out opposition research dedicated to the former reality-television star.

The organization's current research on Trump includes hours of video footage and tens of thousands of pages of potential lines of attack against the presumptive Republican presidential nominee, according to one source familiar with the organization.

Several Democrats with ties to the DNC noted that it's not surprising that the DNC's research in December would be much less complete than the more complete file, once the general election began in earnest.

Former DNC spokeswoman Holly Shulman, who left the committee late last year, said in an email that she was not familiar with the document published in Gawker. But she pointed out that any campaign's research will become a lot more comprehensive as the election nears.

"This looks like a simple summary document," Shulman said of the DNC's file published in Gawker. "Plus, it's six months old, and since then, the DNC's research team became almost 100% focused on building out its Trump book (when I say almost, there is still a VP candidate to watch out for), as it was able to divert staff resources from Jeb, Rubio, Cruz and 12 others as they dropped out of the GOP race."

She added: "Research 'books' aren't one PDF or one file, they are living documents."

The DNC's current research operation is also likely to get another boost.

A source close to the committee said that in recent days, Hillary Clinton's campaign has been in contact with the organization about sharing and coordinating opposition research.

On Thursday, Clinton campaign manager Robby Mook took greater control of the DNC's daily operations, installing a new general-election chief of staff at the DNC to help the organization work directly with the Clinton campaign, aaccording to CNN.

The Clinton campaign declined comment. The DNC didn't respond to repeated requests for comment.