New York City Mayor Bill de Blasio is under fire today for a joke he made over the weekend at a charity event as he performed a skit alongside Democratic presidential candidate Hillary Clinton.

De Blasio endorsed Clinton in October, months after other prominent New York Democrats, including Governor Andrew Cuomo.

She teased him about it during the Saturday evening event, and he told her, 'Sorry Hillary, I was running on C.P. time.'

Clinton jumped in and said that means 'cautious politician' time.

'C.P. time' is actually short for 'colored people' time. As video of the incident made the rounds on Monday, de Blasio was hit 'for making what some said was a 'racist' joke.

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Hillary Clinton (center) made an appearance at the Inner Circle charity show in New York City on Saturday night with mayor Bill de Blasio (right) and Broadway musical Hamilton cast member Leslie Odom, Jr (left)

The Democrat's wife, Chirlane McCray, is black, and the couple has two mixed-race children together.

Nancy Lockhart, a Twitter user supporting Bernie Sanders, said of the incident, 'Being married to a Black woman doesn't give him a pass.'

Jenny Mayer, a New York resident also backing Sanders, called the joke 'racist' and said she was 'offended & disgusted.'

'Is @BilldeBlasio stupid?' asked user Scott Thill.

Jonathan Hines wrote: 'between de Blasio and Jefferson Clinton I think Hillary needs to drop some Bills for the sake of her image'.

The NYC mayor's had problems in the past with racially-charged commentary.

He said at the end of 2014 that he and his wife had advised their black son, Dante, then an attendee of a Brooklyn high school, 'to be very careful' when interacting with police.

'With Dante, very early on, we said, "Look, if a police officer stops you, do everything he tells you to do. Don’t move suddenly. Don’t reach for your cellphone,' " he said on ABC. 'Because we knew, sadly, there’s a greater chance it might be misinterpreted if it was a young man of color.'

He said, 'It’s different for a white child. That’s just the reality in this country.'

National police organizations were up in arms over the statement, which suggested that police in the city de Blasio oversees are predisposed to assume the guilt of black men.

The political union of Clinton and de Blasio has likewise been a rocky one.

He flat-out refused to endorse the former New York senator who still owns a home in the state when she launched her bid last April and waited six months to give her his blessing.

The progressive NYC mayor clashed with Clinton's team last month after pollster Joel Benenson told reporters that his candidate would campaign 'like a senator who represented the state for eight years and lived here for 16' and Sanders would go at it like a 'Brooklynite.'

'I assume the phrase "campaigning like a Brooklynite" is a compliment,' de Blasio said afterward.

Sanders was born in Brooklyn but moved to Vermont as an adult and represents the state in the U.S. Senate.

Clinton made fun of her metro card mishap on April 7 when she tried to take a train in the Bronx and couldn't swipe her pass through the turnstile

de Blasio (pictured) rapped in the style of Hamilton about how reporters are 'like shark week' when they 'attack'

Clinton and de Blasio made nice afterward - he helped her secure her preferred debate day - and surprised guests at the Inner Circle charity event on Saturday night with a skit making fun of her metro card mishap earlier in the week.

The Inner Circle is a parody group of journalists who make fun of government officials. The officials also tease the journalists, according to ABC News.

Proceeds from the night, which took place at the New York Hilton Midtown, go to approximately 100 charities in the city.

The journalists performed a parody of the smash hit musical Hamilton with a skit called 'Shamilton'.

Mayor de Blasio shared the stage with Leslie Odom, Jr, who plays Aaron Burr in Hamilton, and rapped and ribbed with the journalists - and Clinton.

'I love this city and that's a fact but it's like shark week when you reporters attack,' he said.

'I know you're doing your job, so let me do mine. 'Cause I'm BDB, and this is my rhyme,' the mayor rapped.

He and Clinton then performed their skit, taking on her her April 7 trip on the No. 4 train in the Bronx. The finicky subway turnstile wouldn't let Clinton through.

'Do me a favor. Will you just fix these MetroCard slots? It took me like five swipes,' she told de Blasio on Saturday evening. 'The little terminal thing kept saying please swipe again.

'I mean you've got to fix that. You don't have to worry about horses anymore. Fix the turnstile and the MetroCard,' Clinton said.

She also joked that it took de Blasio 'long enough' to endorse her.

The Inner Circle is comprised of local government officials and journalists who poke fun at one another to raise money for nearly 100 charities in New York City

Before she left, she joked: 'And please, can somebody please get me tickets to "Hamilton?"'

Clinton saw the musical Hamilton, for which tickets cost into the thousands when they're not sold out, before it was on Broadway and has quoted the show on her Twitter page before.