Twitter seems to be heavily in favor of Republican presidential candidate Donald Trump, but a sizeable slice of his support comes from social media bots, according to new research.

Analyzing 9 million tweets following the first presidential debate and 11.5 million tweets after the second debate collected from 2 million users, a team of researchers from Oxford University, Corvinus University and the University of Washington found the amount of traffic in pro-Trump hashtags was roughly double the activity in the hashtags of his Democrat rival Hillary Clinton. During the debates themselves, around 40 percent of tweets included pro-Trump hashtags, as opposed to 12 or 13 percent using pro-Clinton hashtags.