The #ObamaGate activity began on 5/9 with #MAGA accounts linking a Fox News clip (later shared by Trump's account) that used the term. One of the early adopters, @SheepKnowMore, is oddly similar to banned #QAnon account @StormIsUponUs and was created a week after the suspension.

The initial #MAGA push failed to cause #ObamaGate to trend. Shortly after midnight 5/10, @AnaPaulaVolei used the hashtag in a Portuguese-language tweet that was massively amplified, largely by accounts that like to tweet pro-Bolsonaro hashtags.

While we can't prove it, our working hypothesis is that the retweets of @AnaPaulaVolei's tweet caused it to trend regionally in Los Angeles (her profile location) before it trended nationally; several of the accounts that first commented on it trending are L.A. or SoCal-based.

Once the trend finally got in full swing the morning of 5/10, #MAGA opportunism wasn't far behind. GOP Congressional candidate @ErrolWebber wasted no time in using it to promote his campaign website, and was rewarded with a multitude of retweets.

Update: the #QAnon contingent has discovered this thread and weighed in with various bits of #QAnonsense.