Protecting Special Counsel Robert Mueller will be one of the main issues discussed at the US Congress being held on Tuesday at a post-election session.
It comes as news emerged Tuesday that Trump is expected to provide written answers to questions this week concerning Moscow's involvement in his election, a source familiar with the matter told Reuters.
Former FBI director Mueller is currently leading an inquiry into Russian interference in the 2016 US presidential election and examining whether the Trump campaign colluded with Russia to bring Trump to victory.
At the "lame-duck" discussion in Congress, Democrats and some Republicans want to establish regulations to prevent President Donald Trump from hindering or ending Mueller's work.
Trump has stressed that the Mueller investigation is a "witch hunt" and firmly rejects that he or his associates conspired with Russia. Russian President Vladimir Putin has said his country did not get involved in the election.
Democrats and some Republicans are concerned that Trump is now preparing to dismiss or impede Mueller.
Trump sacked Attorney General Jeff Sessions, last week, and replaced him with Matthew Whitaker as acting attorney general in charge of the Mueller case.
Whitaker will have the power to dismiss Mueller or terminate the investigation and said he has concerns over the case being too broad and extensive.
Democratic senator Richard Blumenthal told US media that he is considering legal action over the Whitaker appointment.
Blumenthal's staff was trying to start a legal battle against Trump, according to an advisor.