White House Press Secretary Sean Spicer is likely to face another round of questioning over a Senate judiciary subcommittee hearing on Russia’s role in the 2016 elections during his Tuesday news briefing.

Spicer is scheduled to begin speaking at 1:30 p.m. EST. Watch live in the player above.

On Monday, former acting Attorney General Sally Yates said she bluntly warned the Trump White House that new National Security Adviser Michael Flynn “essentially could be blackmailed” by the Russians because he apparently had lied to his bosses about his contacts with Moscow’s ambassador in Washington.

The congressional testimony from Yates, an Obama administration holdover fired soon after for other reasons, marked her first public comments about the concerns she raised and filled in basic details about the chain of events that led to Flynn’s ouster in February.

WATCH: Former acting AG Sally Yates to testify in Russia probe

Her testimony, coupled with the revelation hours earlier that President Barack Obama himself had warned Donald Trump against hiring Flynn shortly after the November election, made clear that alarms about Flynn had reached the highest levels of the U.S. government months before. Flynn had been an adviser to Trump and an outspoken supporter of his presidential candidacy in the 2016 campaign.

Yates, appearing before a Senate panel investigating Russian interference in the election, described discussions with Don McGahn, the Trump White House counsel, in which she warned that Flynn apparently had misled the administration about his communications with Sergey Kislyak, the Russian ambassador.

MORE: Trump distances himself from Flynn as Russia probe continues

White House officials, including Vice President Mike Pence, had insisted that Flynn had not discussed U.S.-imposed sanctions with Kislyak during the presidential transition period. But they asked Flynn to resign after news reports indicated he had lied about the nature of the calls.

Trump’s press secretary Sean Spicer said in response that if Obama “was seriously concerned” about Flynn’s connections to Russia or other foreign countries, he should have withheld Flynn’s security clearance. Flynn served under Obama as defense intelligence chief before Obama dismissed him.

WATCH: Spicer says Obama made clear to Trump he ‘wasn’t exactly a fan’ of Michael Flynn

Trump repeatedly has said he has no ties to Russia and isn’t aware of any involvement by his aides in any Russian interference in the election. He’s dismissed FBI and congressional investigations into his campaign’s possible ties to the election meddling as a “hoax” driven by Democrats bitter over losing the White House.

After the hearing Monday, Trump tweeted: “The Russia-Trump collusion story is a total hoax, when will this taxpayer funded charade end?”

READ MORE: What we know about U.S. investigations into Russia and possible ties to Trump’s campaign

PBS NewsHour will update this story as it develops.