Supporters of Bernie Sanders Bernard (Bernie) SandersSenate Dems seek to turn tables on GOP in climate change fight Bernie Sanders Town Hall finishes third in cable news race, draws 1.4 million viewers Woman to undecided Biden: 'Just say yes' to 2020 bid MORE expressed outrage and suspicion after reports of an email sent to Hillary Clinton Hillary Diane Rodham ClintonREAD: Cohen testimony alleges Trump knew Stone talked with WikiLeaks about DNC emails County GOP in Minnesota shares image comparing Sanders to Hitler Holder: 'Time to make the Electoral College a vestige of the past' MORE supporters with an image labeled "secret win" surfaced shortly after The Associated Press said she had secured the Democratic presidential nomination.

The AP based its declaration on its own delegate count, including superdelegates. But Sanders supporters say that is unfair because the unbound party leaders could potentially switch their support at any time in the weeks leading up to the Democratic National Convention in July.

#SecretWin #ElectionFraud This election continually reveals exactly the true nature of everyone involved. Dont be fooled by team colors. — Rebel_Love (@EbenGreyrose) June 7, 2016

#SecretWin Hillary and the medias way of bringing voters to heel. Your blatant cheating has turned half your party #BernieOrBust. Congrats! — Kid Stardust (@SvenSveetheart) June 7, 2016

Sorry, yesterday I said there was no proof of collusion. Is #SecretWin the smoking gun? https://t.co/DXv7ZbDRzZ — Keith Kahn (@keithkahn) June 7, 2016

Many Sanders supporters have voiced suspicions that Democratic Party leaders have rigged the primary against him to make sure Clinton wins the nomination.

Actor Tim Robbins, an outspoken Sanders supporter, blamed his loss in the New York primary on voter fraud, saying the “election is being stolen."