"If they want me to do a drug test, a urine test, I'll do one right now," Ford tells Black in an interview scheduled to air Monday at 9 p.m. ET. "If there's any drugs in my system, any alcohol in my system. I have no problem doing that test."
Ford's quote comes from a short excerpt of the interview, posted on the website of Vision TV, which is owned by ZoomerMedia. The full interview is scheduled to air Monday.
In recent weeks, Ford has admitted to smoking crack cocaine, faced allegations of excessive alcohol use and had many of his powers taken from him in a city council vote.
Ford's at-times erratic behaviour has also made him the subject of regular ridicule on late-night U.S. talk shows.
Montreal-born Black, who was convicted in 2007 of fraud and obstruction of justice and released from a U.S. prison in 2012, also has a video editorial posted on Vision's website in which he says the "piling on" against Ford in the media has been "excessive."
"He was elected mayor of Toronto and those who do not like his style will be free to vote against him if he runs again," said Black.
"If there is sufficient evidence to charge him with crimes, due process should be followed, but he should be accorded a full presumption of innocence unless he is justly convicted. Beyond that, his accusers should put up or shut up."
Ford has embarked on a blitz of selective television interviews since the scandal surrounding him caught fire last month.
Monday's interview will bring together two men of almost opposite styles.
Though both are ardent conservatives, Ford comes across as the folksy everyman who loves football; Black is known for writing weighty tomes about U.S. presidents and showing off his expansive vocabulary.