Sally Yates, the former U.S. attorney in Atlanta and former acting U.S. attorney general, is set to testify Monday before the U.S. Sen. Lindsey Graham-led subcommittee. CNN has picked up some info as to what she's likely to say:

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.