CNN political commentator Jeffrey Lord compared a progressive group leading the charge against Republican presidential front-runner Donald Trump to the Ku Klux Klan on Tuesday.

In an op-ed for the American Spectator, the former Reagan Administration official and outspoken Trump supporter railed against MoveOn.org, a group whose leaders took credit for the massive protests at Trump's Chicago rally last Friday and have promised more disruptions.

"Meet MoveOn.org. The new Ku Klux Klan. The newest leftist incarnation of that old leftist formula that combines racism with violence to push the progressive agenda," Lord wrote.

According to Lord, the progressive group has become "the latest successor" to the "mantle of racism" in America. He cited the group's staged protests at Trump's rally last week and a Bernie Sanders supporter's heckling at another Trump campaign event as examples of the progressive push to silence the New York billionaire.

"From the thuggish behavior, the pre-disposition to violence and racism not to mention the sense of moral and intellectual superiority, not a thing here is new," Lord wrote. He said the group, "in the finest traditions of the Klan, organized a mass shutdown that was specifically directed to people because of their race."

"The only difference between this and the days when the progressives were hiding under those white hoods and burning crosses while trying to terrorize newly freed slaves and their white allies? This time around they don't use hoods and burning crosses to rally the terrorists, they use social media instead," he added.

Hours after Lord's op-ed was published Tuesday, MoveOn.org posted an open letter to its progressive allies that calls for "massive nonviolent mobilization" against Trump.

"[T]oday we are calling for a massive nonviolent mobilization of working people, students, immigrants, children of immigrants, great-great-grandchildren of immigrants, people of color and white people, the unemployed and under-employed, people of faith, retirees, veterans, women, and men — anyone who opposes bigotry and hate and loves freedom and justice — to stand up to Trump's bullying and bigotry," the group wrote in its letter.

At press time, 21 progressive organizations, such as NARAL Pro-choice America and the SEIU, had signed the letter.