Civil Rights activist Rev. Jesse Jackson Sr. attended the Rainbow/PUSH Coalition convention in Chicago on Thursday, where he claimed President Donald Trump stole the election.

Jackson was introducing the Democratic National Committee chairman Tom Perez when he made the accusation against Trump.

"To have a head of our party who is sensitive to the plight of working people is the order of this day," Jackson told the crowd. "Don’t forget when you lose, you tend to amplify ‘would’ve, could’ve, should’ve.’ When you win you cover up your sins."

"We worked last year. We won the election. It was stolen," Jackson concluded.

Jackson is not the first Democrat to accuse Trump of stealing the presidential election from Hillary Clinton last November. Pro-Clinton operative David Brock delivered a speech back in January at a Florida donors' retreat, where he accused Trump and then-FBI director James Comey of stealing the election.

Several Democratic lawmakers have suggested that Trump's presidency is "illegitimate," including Reps. John Lewis (D., Ga.) and Ted Lieu (D., Calif.). They have claimed that the American people have an "illegitimate" president occupying the White House.