Occupy protesters have amped up May Day labor demonstrations across the country with a wide range of partnering organizations and individuals. Former 60s anti-war activist William "Bill" Ayers is among those protesting in Chicago on Tuesday.
He said he planned to participate in the May Day demonstration at Union Park in Chicago and the subsequent march.
"We'll march right past the scene of the Haymarket massacre," Ayers said of the protest in favor of an eight-hour work day in 1886 that was bombed. "There used to be a big statute in tribute to police power but it was taken down. Now there's a wonderful piece of public art celebrating the movement for labor rights and the anarchists' movement.
Ayers is a retired professor of education reform at the University of Illinois at Chicago and author of multiple books, including "Fugitive Days: Memoirs of an Anti-War Activist" from 2009 and "To Teach: The Journey, in Comics" from 2010.
He and his wife, Bernadine Dohrn, former leaders of the radical anti-war group the Weather Underground, paid a visit to Occupy Wall Street protesters in Union Square Park in New York on March 30.
In a call with ABC News, Ayers declined to comment about that meeting.
Ayers said he has participated in May Day labor demonstrations "for about 50 years."
"May Day is an international workers holiday all over the world. Only in U.S. do we not celebrate that history."
Dohrn is a clinical associate professor of law at Northwestern University School of Law and founder of its Children and Family Justice Center.
Ayers did not mention the May Day protests on his blog, instead drawing attention to a petition on April 29 opposing educational "privatization while undermining public education."
Ayers was a flashpoint for a brief controversy during the 2008 presidential campaign. Opponents of Barack Obama criticized the then candidate for having ties to the former radical. Ayers later disputed the claim, writing an op-ed in the New York Times.
ABC News' Susanna Kim contributed to this report.