Deputy Attorney General Rod Rosenstein knew that FBI Director James Comey would be removed before he penned a now-famous memo that was cited by the White House as rationale for the firing, Democratic senators said Thursday after a briefing with the senior DOJ official.

Rosenstein, who a day earlier named a special counsel to oversee the Russia probe that Comey was helping lead before his ouster, briefed all U.S. senators on Capitol Hill Thursday.

Coming out of that briefing, lawmakers said Rosenstein revealed that President Trump’s decision preceded his letter.

“He knew that Comey was going to be removed prior to him writing his memo,” Sen. Claire McCaskill, D-Mo., said.

Sen. Dick Durbin, D-Ill., also said Rosenstein learned on May 8 that Trump “was going to terminate Comey.”

Rosenstein wrote the memo on May 9.

Justice Department officials however who were in the room told Fox News that Rosenstein was not directly affirmative on that point, but rather, conveyed to the Senators in the briefing that he got the sense that President Trump was strongly leaning towards firing Comey before Rosenstein wrote his memo. 

Officials stressed to Fox News that Rosenstein was not told outright that Trump was going to terminate Comey, and therefore wrote a memo to lay out the reasoning.

The memo is a critical factor, as the Trump administration initially cited Rosenstein’s assessment in its explanation for Comey’s firing last week. Rosenstein had castigated Comey over his handling of the Hillary Clinton email probe.

On Thursday, Sen. Lindsey Graham, R-S.C., told reporters after the briefing that Rosenstein did find Comey’s actions “inappropriate” with regard to the Clinton probe. But the revelations about the timeline dovetail with more recent statements from Trump that he planned to fire Comey regardless of any DOJ recommendation.

Some Democrats have suggested all along that the Comey memo was used as pretext to remove the FBI director helping lead the probe into Russian meddling in the 2016 race and alleged ties to Trump associates.

The White House has defended its actions, and continues to deny any collusion with Russia during the 2016 campaign.

At a press conference later Thursday afternoon, Trump again cited the “strong recommendation” and “very, very strong letter” from Rosenstein in his decision – along with other factors.

He said Comey was “very unpopular with most people,” and cited the recent congressional hearing for which Comey had to “readjust the record” on one point. Trump also criticized the decision to name a special counsel in the Russia probe.

But lawmakers of both parties largely praised the naming of former FBI director Robert Mueller to oversee that investigation. Senators said Thursday that Rosenstein made clear in the briefing he was giving Mueller leeway to do the job.

McCaskill said he would have “complete discretion to take the investigation” where it needs to go.

Trump earlier Thursday called the probe a “witch hunt.” And during a lunch with reporters, he said the special counsel appointment is bad for the country.

“I believe it hurts our country terribly, because it shows we're a divided, mixed-up, not-unified country,” he said. “And we have very important things to be doing right now, whether it's trade deals, whether it's military, whether it's stopping nuclear -- all of the things that we discussed today. And I think this shows a very divided country.”

He also suggested the Russia claims are an “excuse” being used by the Democrats to explain their 2016 election loss.  

“I think it's a very, very negative thing. And hopefully, this can go quickly, because we have to show unity if we're going to do great things with respect to the rest of the world,” he said. 

Rosenstein had much to cover in the long-awaited Senate briefing, including the Comey firing, the naming of a special counsel and the Russia probe itself.

The briefing was on the books before Rosenstein announced Wednesday that he had named Mueller to take over the investigation.

In a statement, Rosenstein said he decided to hand off the high-profile investigation to an independent investigator, “in order for the American people to have full confidence in the outcome.”

“In my capacity as acting Attorney General, I determined that it is in the public interest for me to exercise my authority and appoint a Special Counsel to assume responsibility for this matter," Rosenstein said. "My decision is not a finding that crimes have been committed or that any prosecution is warranted.”

The appointment gives Mueller, who led the FBI through the Sept. 11 terrorist attacks and served under presidential administrations of both parties, sweeping powers to investigate whether Trump campaign associates colluded with the Kremlin to influence the outcome in his behalf, as well as the authority to prosecute any crimes uncovered during the probe. 

The Justice Department said Mueller has resigned from his job at a private law firm to take the job of special counsel.

In a related development, former CIA director John Brennan is now expected to appear before the House Intelligence Committee next week to answer questions on the Russia investigation. 

Fox News' Judson Berger, Catherine Herridge, Jake Gibson, Bret Baier and Chris Wallace and The Associated Press contributed to this report.