CNN chief White House correspondent Jim Acosta slammed “dishonest, deceptive” President Trump and mocked Press Secretary Sarah Sanders’ briefings on Monday at a CNN event in New York.

“I wouldn’t put productive and a Sarah Sanders briefing in the same sentence,” Acosta said when asked if it’s more productive to hear from the press secretary or from Trump directly.

Acosta -- who is billed as an impartial journalist -- declared that Sanders typically aims to “perform for the president” in order to maintain her own job security. He was part of a panel discussion at Citizen by CNN, a daylong event that featured a variety of panel discussions.

Acosta was on stage for a discussion moderated by CNN’s Wolf Blitzer that also featured New York Times reporter Maggie Haberman and White House Correspondents’ Association president Olivier Knox when the CNN reporter aired his grievances about covering the Trump administration.

“Many of us didn’t expect Trump to win and it sort of turned the beat upside down,” Acosta said. “We need security wherever we go, covering these rallies… you are under attack by the press office of the White House... you sort of have to rise above that and keep plowing through and do your job."

Trump has famously dubbed CNN “fake news” and pointed directly at Acosta, calling him by that disparaging moniker in the past. Acosta said he’s been told by many people that Trump’s persona is simply an “act,” and that his supporters don’t realize that when the president refers to news organizations as “fake news” it is simply part of his “shtick.”

“They think he’s deadly serious so they take up the cause and they come after us,” Acosta said. “The United States of America is supposed to be the standard bearer for democratic values all over the world. For the president of the United States to go around calling us ‘fake news’ and the ‘enemy of the people,’ to me, I don’t understand why this is even a debate or a discussion for journalists. It’s just wrong.”

Acosta then said that Trump supporters typically have a negative view of the mainstream media because it spends “a lot of the time fact checking” the president.

“It drives people crazy because we’re constantly pointing out these falsehoods,” Acosta said. “It’s lie, after life, after lie.”

Acosta said he feels comfortable calling inaccurate statements “lies,” as opposed to things such as “whoppers” and falsehoods,” because, he alleged, Trump is a “dishonest, deceptive person” who built his political career on lies.

CNN stars Dana Bash, Carl Bernstein, Wolf Blitzer, Kate Bolduan, Gloria Borger, Van Jones, John King, Brian Stelter and Jake Tapper also participated in the event. Non-CNN guests included Watergate legend Bob Woodward, New York Times publisher A.G. Sulzberger, U.S. House Minority Leader Nancy Pelosi, Jeff Flake and White House adviser Jared Kushner.

Last week, Acosta apologized for saying ‘f-ck you” to a former Melania Trump staffer in a private Twitter message after the chief White House correspondent was widely criticized for the vulgar attack.

Acosta took the opportunity to poke fun at the situation on stage Monday when Blitzer asked how he was doing.

“Occasionally you send a DM and everybody overreacts,” Acosta said.

Acosta – who is frequently mocked by Trump supporters – was widely criticized on social media for the comment. He has also made a habit of shouting and interrupting when Trump and members of his administration are available to the media.

Earlier this year, Trump kicked the CNN star out of the Oval Office after Acosta badgered the president with racially charged questions. Acosta has also gotten into combative arguments with other members of the administration including former Press Secretary Sean Spicer, Management and Budget Director Mick Mulvaney and Senior Policy Adviser Stephen Miller.