Deputy Attorney General Sally Q. Yates speaks during a press conference at the Department of Justice on June 28, 2016 in Washington, DC.
Pete Marovich/Getty Images
Deputy Attorney General Sally Q. Yates speaks during a press conference at the Department of Justice on June 28, 2016 in Washington, DC.
Now playing
02:07
Sources: Yates to contradict WH on Flynn
Now playing
01:42
A vaccine without needles? It's on the way
Now playing
03:44
Do the 1990s hold the key to sustainable websites?
Now playing
02:52
Businesses set vaccine mandate for workers
Now playing
05:52
The climate crisis is taking these farmers' most valuable resource
SAN FRANCISCO, CA - FEBRUARY 06:  Host Conan O'Brien speaks onstage during the 5th Annual NFL Honors at Bill Graham Civic Auditorium on February 6, 2016 in San Francisco, California.  (Photo by Tim Mosenfelder/Getty Images)
Tim Mosenfelder/Getty Images
SAN FRANCISCO, CA - FEBRUARY 06: Host Conan O'Brien speaks onstage during the 5th Annual NFL Honors at Bill Graham Civic Auditorium on February 6, 2016 in San Francisco, California. (Photo by Tim Mosenfelder/Getty Images)
Now playing
01:48
Conan announces his last show after 30 years in late night
Now playing
03:41
How technology at NASA helps guide Biden on climate
Drew Angerer/Getty Images
Now playing
03:14
Will Trump be allowed back on Facebook? This board will decide
CNN
Now playing
05:16
WTF is a SPAC?
Now playing
01:51
A shortage of tanker truck drivers could cause stations to run out of gas
CEO at Verizon Media K. Guru Gowrappan appears at the 2019 Verizon Media NewFront on April 30, 2019 in New York City.
Noam Galai/Getty Images for Verizon Media
CEO at Verizon Media K. Guru Gowrappan appears at the 2019 Verizon Media NewFront on April 30, 2019 in New York City.
Now playing
02:47
Verizon sells off Yahoo and AOL
Warren Buffett, CEO of Berkshire Hathaway, attends the 2019 annual shareholders meeting in Omaha, Nebraska, May 3, 2019. (Photo by Johannes EISELE / AFP)        (Photo credit should read JOHANNES EISELE/AFP via Getty Images)
Johannes Eisele/AFP/Getty Images
Warren Buffett, CEO of Berkshire Hathaway, attends the 2019 annual shareholders meeting in Omaha, Nebraska, May 3, 2019. (Photo by Johannes EISELE / AFP) (Photo credit should read JOHANNES EISELE/AFP via Getty Images)
Now playing
02:40
Warren Buffett warns on US inflation
Now playing
01:00
Astronauts splash down after record-setting mission
ATLANTA - APRIL 30:  A Boeing 757 with a new Delta Airlines logo sits on the tarmac following the company's emergence from bankruptcy at Hartsfield Jackson International Airport April 30,2007 in Atlanta, Georgia. The 757 sports new branding that will appear on more than 900 planes, at airports and on advertising.  (Photo by Barry Williams/Getty Images) 757
Barry Williams/Getty Images North America/Getty Images
ATLANTA - APRIL 30: A Boeing 757 with a new Delta Airlines logo sits on the tarmac following the company's emergence from bankruptcy at Hartsfield Jackson International Airport April 30,2007 in Atlanta, Georgia. The 757 sports new branding that will appear on more than 900 planes, at airports and on advertising. (Photo by Barry Williams/Getty Images) 757
Now playing
02:28
Why Delta airlines is resuming selling middle seats
Now playing
02:50
Grocery chain says 'hero pay' forcing them to close stores
Getty Images
Now playing
02:54
Jimmy Kimmel is worried about MyPillow's Mike Lindell
(CNN) —  

Former Acting Attorney General Sally Yates is prepared to testify before a Senate panel next week that she gave a forceful warning to the White House regarding then-National Security Advisor Michael Flynn nearly three weeks before he was fired, contradicting the administration’s version of events, sources familiar with her account tell CNN.

In a private meeting January 26, Yates told White House Counsel Don McGahn that Flynn was lying when he denied in public and private that he had discussed US sanctions on Russia in conversations with Russian Ambassador to the US Sergei Kislyak. Flynn’s misleading comments, Yates said, made him potentially vulnerable to being compromised by Russia, according to sources familiar with her version of events. She expressed “serious concerns” to McGahn, making it clear – without making a recommendation – that Flynn could be fired.

Yates’ testimony May 8 will be the first time the former acting attorney general will publicly speak about the White House meeting. A source familiar with the situation says that Yates will be limited on what she can tell the Senate judiciary subcommittee because many of the details involving Flynn are classified, meaning there may only be a few new revelations.

Yates would not comment ahead of the testimony.

Her previously scheduled appearance in front of the House intelligence committee was canceled by its chairman Rep. Devin Nunes, R-California, who said he wanted to hear first in a classified setting from FBI Director James Comey and National Security Agency Director Mike Rogers. Nunes’ move to cancel the hearing sparked outcry from Democrats, who believed he was trying to shield the White House from damaging new revelations.

Flynn was fired 18 days after Yates met McGahn, following news reports that Flynn had lied to Vice President Mike Pence about his conversations with the Russian ambassador.

On February 14, the day after Flynn’s firing, White House press secretary Sean Spicer told reporters that Yates had simply “wanted to give a ‘heads up’ to us on some comments that may have seemed in conflict with what he (Flynn) had sent the Vice President.”

Yates is highly motivated to set the record straight about her warning regarding Flynn, one source said.

But because of the classified nature of the information, she is unlikely to explain in detail what specific information prompted her to raise concerns with the White House about his alleged ties to the Russians. She is, though, expected to give her version of events when she informed the White House about her concerns that Flynn may have been “compromised” by the Russians, contradicting Spicer’s comment that Yates was simply giving officials a “heads up” about the then-national security advisor, the source said.

Her appearance will bookend a week’s worth of testimony and inquiry about the investigation, starting with Wednesday’s Senate judiciary committee hearing with Comey, where Russia will be a big topic of discussion. Comey is also expected to meet behind closed doors Thursday with members of the House intelligence committee.

The Senate judiciary subcommittee hearing Yates’ testimony is also seeking to have former national security advisor Susan Rice testify before the committee next week, Sen. Lindsey Graham, R-South Carolina, the chairman of the panel, told CNN.

Comey will likely resist revealing much about the ongoing investigation into Russia’s efforts around the 2016 election. But committee members are seeking to press him. Republicans will likely seek answers on how the FBI worked with Christopher Steele, the former British spy who created the reports on Trump that make up the controversial dossier. CNN was first to report in January that both then-President Barack Obama and then-President-elect Trump were briefed on the contents of the dossier by senior intelligence officials.

Democrats will push Comey on what has been learned about campaign contact, according to Democrats on the committee. Sens. Chris Coons of Delaware and Richard Blumenthal of Connecticut say they will also seek answers on why Comey spoke publicly about an investigation into Hillary Clinton but not about the Russia investigation that kicked off in the summer of the campaign. Comey, according to sources familiar with his testimony, is looking to set the record straight on this matter.

The hearing is not solely focused on the probe, a contrast to his previous appearance on the Hill. But the Yates appearance next week, at the same hearing as former Director of National Intelligence James Clapper, is perhaps the most dramatic.

Yates is prepared to answer as much as she can in an unclassified setting, the source added. But, another source said, Yates is not expected to say much about the wider Russia probe.

CNN’s Gloria Borger contributed to this report.