Hillary Clinton slammed Donald Trump on Twitter on Monday for tweeting what she described as a “debunked study” that suggests “millions” of voters in 2016 were manipulated in her favor.

Fox News reported that the latest dispute between the former 2016 presidential candidates started when Trump tweeted the unverified claim that Google “manipulated from 2.6 million to 16 million votes for Hillary Clinton in the 2016 election.”

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

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

— Donald J. Trump (@realDonaldTrump) August 19, 2019

The tweet appears to refer to claims made by Robert Epstein, of the American Institute for Behavioral Research and Technology, who alleged that Google used what he described as the “Search Engine Manipulation Effect” to sway at least 2.6 million votes toward Clinton. He made these claims at a Senate hearing back in June, and many members of the media claimed they were totally inaccurate.

“This is one claim from one person that, as far as I can tell, hasn’t been peer-reviewed or replicated. On its surface, it’s dubious, as is the methodology underlying it. It’s the sort of thing that people in positions of authority – such as, say, a senator or a president – might be cautious about spreading,” wrote Philip Bump of The Washington Post.

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Clinton seems to agree with Bump.

“The debunked study you’re referring to was based on 21 undecided voters,” Clinton tweeted directly to Trump. “For context that’s about half the number of people associated with your campaign who have been indicted.”

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

— Donald J. Trump (@realDonaldTrump) August 19, 2019

Judicial Watch, which Trump had tagged in his initial tweet, released their own statement they considered the shoutout to be “encouragement that Judicial Watch investigate this issue as part of our Election Integrity Project.”

Clinton and Trump have gone back and forth numerous times since he won the 2016 presidential election. It remains to be seen if he will actually respond to her latest attack.