Former FBI Director James Comey doesn't agree with Attorney General William Barr's assertion Wednesday that "spying did occur" on President Trump's 2016 campaign.

"The FBI conducted court-ordered authorized surveillance. I don't consider that spying," Comey said at the Hewlett Foundation's Verify Conference on Thursday.

Although Comey said he gives Barr the benefit of the doubt, citing his long career, his talk of "spying" makes it more difficult. "I have no idea what the heck he's talking about," Comey added.

Barr sparked an uproar among Democrats and the media Wednesday during his testimony to a Senate budget panel.

"I think spying did occur. But the question is whether it was predicated — adequately predicated," Barr testified. "I'm not suggesting it wasn't adequately predicated, but I need to explore that. I think it's my obligation. Congress is usually very concerned about intelligence agencies and law enforcement agencies staying in their proper lane."

"I think spying on a political campaign is a big deal. It's a big deal," Barr added, an apparent reference to GOP allegations that the FBI misled the Foreign Intelligence Surveillance Court to monitor former Trump 2016 campaign foreign policy adviser Carter Page.

However, later in the hearing, Barr clarified he hasn't proven there was any wrongdoing. “I am not saying that improper surveillance occurred, I'm saying that I am concerned about it and looking into it, that's all," he said.

Still, Barr's "spying" bombshell has riled Democrats.

At a Democratic retreat, House Speaker Nancy Pelosi, D-Calif., said Barr went "off the rails." House Judiciary Committee Chairman Jerry Nadler, D-N.Y., demanded a briefing from the Justice Department while Senate Minority Leader Chuck Schumer, D-N.Y., called for an immediate retraction.

An Obama-era Justice Department chief took issue with the "spying" comment."When there is a predicate, a legitimate basis, it’s called 'investigating' not 'spying'. I am confident that the people at DOJ/FBI conducted themselves in an appropriate way. No evidence to suggest otherwise," Eric Holder tweeted.

Republicans defended Barr. "Unfortunately, the Democratic party wants an outcome when it comes to Trump, not a process. Mueller was allowed to do his job, and I am confident that Attorney General Barr is accurately representing the conclusions of the Mueller investigation," Senate Judiciary Committee Chairman Lindsey Graham, R-S.C., tweeted.

Comey has criticized Trump and his allies past claims that his campaign was subject to politically motivated spying. ""As best I can tell, it's made up. I don't know where he's getting that from, honestly," Comey said during an interview with late-night host Conan O'Brien during the "Spygate" controversy last year.

Barr, who is putting a team together to look into surveillance abuse, also testified he expects to release a redacted version of special counsel Robert Mueller's final report "hopefully next week." Mueller was appointed as special counsel days after Comey was fired by Trump as FBI director in May 2017.

The Judiciary Committee, ruled by Democrats, voted last week in favor of subpoenaing Barr to turn over the entire Mueller report. However, Nadler said on Tuesday that his panel, which has oversight over DOJ, will not actually issue a subpoena for Mueller's full report until they see the redacted version provided by Barr.