Trump 'planning smear campaign' against Sally Yates while she testifies against administration in Russia probe
Ms Yates will give evidence about alleged Russian meddling in the 2016 presidential election and possible collusion between the Trump campaign and the Kremlin.
James Clapper, the Director of National Intelligence in Barack Obama’s Administration will also testify.
The White House planned on branding Ms Yates a “Democratic operative” intent on sabotaging Mr Trump, who was willing to twist facts, news website Axios reported.
Yates to testify she warned White House about Flynn's Russia links
Distancing the President from his former National Security Advisor Lt Gen Michael Flynn and depicting him as solely to blame for the scandal, was also part of the strategy.
General Flynn was forced to resign in December after less than a month in office, when it emerged that he had met with Russian ambassador Sergei Kislyak to talk about the possibility of removing US sanctions after Mr Trump came to power and then misled Vice President Mike Pence and other top White House officials about his conversations.
Ms Yates is expected to tell senators that on 26 January, when she was still acting Attorney General, she warned the White House Counsel Don McGahn about General Flynn's conversations.
Congressional committees began their investigations after US intelligence agencies concluded that hackers targeting the Democratic Party could be traced back to Russia.
In July, on the eve of the Democratic National Convention, Wikileaks published 20,000 internal emails stolen by the hackers.
US intelligence officials said they believed with "high confidence" that Russia was behind the operation, but the Trump campaign publicly refused to accept the findings. Moscow has also denied the allegations.
The public hearing will be the first featuring testimony by Obama administration officials who have since left government.
Mr Trump fired Ms Yates from the Department of Justice in January, after she ordered federal attorneys not to defend his controversial immigration order.