Chuck Rosenberg, a former FBI chief of staff under former Director James Comey, on Monday said collusion is “absolutely a crime,” a day after President Trump’s lawyer Rudy Giuliani said it was not a crime.

“Collusion is a crime,” Rosenberg said on MSNBC's "MTP Daily." “We just happen to call it something else, we call it conspiracy, but it is absolutely a crime.”

“You probably won’t find the crime bank heist in the criminal code but bank robbery is a crime too, and so I am sort of perplexed that it has come down to synonyms,” said Rosenberg, who once headed the Drug Enforcement Administration.

“If these folks don’t know that collusion and conspiracy are synonyms for one another and this is a legal strategy, then they might want to consider changing horses in this race,” Rosenberg added.

In several interviews on Monday, Giuliani asserted that collusion is not a crime.

“I have been sitting here looking in the federal code trying to find collusion as a crime,” Giuliani said on “Fox & Friends.” “Collusion is not a crime.”