Democrats have stepped up their attacks on Attorney General Jeff Sessions, saying his explanation regarding his contacts with the Russian ambassador in 2016 were "simply not credible".
House Democratic leader Nancy Pelosi insists Mr Sessions should step down.
But President Donald Trump said he was "an honest man" and called the Democrat attacks "a total witch hunt".
Mr Sessions earlier removed himself from an FBI inquiry into alleged Russian meddling in the US election.
But he said he did not lie at January's confirmation hearing, when he said he had "no communications with the Russians".
He insisted his comments at his confirmation hearing were "honest and correct as I understood it at the time".
Mr Sessions was speaking after it had emerged that he met Russian ambassador Sergei Kislyak twice last year.
Mr Sessions was at the time a member of the Senate Armed Services Committee. But he was already a prominent member of Donald Trump's campaign team.
In a separate development on Thursday, a White House official said Mr Trump's son-in-law Jared Kushner and ousted National Security Adviser Michael Flynn met Mr Kislyak in December - after the 8 November election.
The official was speaking on the condition of anonymity.
Mr Flynn was fired last month after he misled the White House about his conversations with the Moscow diplomat, allegedly regarding US sanctions.
Claims of Kremlin interference have dogged President Trump.
In a series of tweets on Thursday, President Donald Trump defended Mr Sessions.
He admitted Mr Sessions "could have stated his response more accurately" but said it was "clearly not intentional".
He said the Democrats were carrying out a witch hunt to try to save face for losing the election.
He added: "The real story is all of the illegal leaks of classified and other information."(Source: BBC)