President Donald Trump on Aug. 19 drew attention to research that shows the sway Google holds over election results after a former engineer for the company came forward with a pile of internal documents suggesting political interference.

“Wow, Report Just Out! Google manipulated from 2.6 million to 16 million votes for Hillary Clinton in 2016 Election!” Trump wrote. “This was put out by a Clinton supporter, not a Trump Supporter! Google should be sued. My victory was even bigger than thought!”

Trump was most likely referring to the work of Robert Epstein, a research psychologist at the American Institute for Behavioral Research and Technology in California, who’s studied for years how much influence Google has on its users’ political views and voting.

In a Feb. 18, 2016, essay, Epstein said that Google had “the power to drive between 2.6 and 10.4 million votes to Clinton on election day with no one knowing that this is occurring and without leaving a paper trail.”

Based on his monitoring of Google search results on election day in 2016 and in the weeks prior, Epstein determined that there was indeed a pro-Clinton bias in the results and that 2.6 million votes were shifted. He said he personally supported Clinton in the race.

Google previously criticized Epstein’s research as “flawed.” Epstein retorted by saying Google failed to rebuke his arguments in substance.

A Google executive told Congress last month that the company’s products are designed and operated to be politically neutral.

It’s not clear why Trump referred to 16 million in his tweet.

Leaked Documents

Epstein’s research has been recently highlighted due to his congressional testimony on July 16.

In recent days, he’s offered comments and analysis on the nearly 1,000 pages of internal documents released on Aug. 14 by former Google software engineer Zachary Vorhies.

In an Aug. 14 interview with Breitbart Radio, Esptein argued that Google executives have committed perjury by telling Congress the company doesn’t “rerank” search results and doesn’t have blacklists.

Epstein pointed out that the trove of leaked documents includes two blacklists. One of the lists, marked as “manual”—meaning made by humans—contains a number of fringe political websites of which most appear to lean right. It also includes some mainstream conservative-leaning websites such as dailycaller.com, and news watchdog newsbusters.org.

The blacklist indicates the sites are blocked from the feed that shows up below the search bar in the Google mobile app.

The list marks many of the sites as having a “high user block rate.” It’s not clear why these sites would need to be blacklisted manually if a high block rate alone automatically placed them on the list.

Epstein also noted that one of the leaked documents describes how to create a “twiddler”—a program that tweaks search results by, for example, pushing certain results up and others down based on criteria specified by the programmer.

“They literally rerank search results to meet their ever-changing needs, and some of those needs are political needs,” Epstein said.

The documents Vorhies provided, together with his explanations and hidden camera recordings by Project Veritas of other Google employees, indicate that the company has created a concept of “algorithmic fairness”through which it infuses the political preferences of its mostly left-leaning workforce into its products.

Several studies have shown that the Google News product itself is biased to the left.

Epstein warned that in 2020, if companies such as Google and Facebook all support the same candidate, they will be able to shift 15 million votes—a margin surpassed by only a handful of presidents.