WASHINGTON, D.C (NBC) — The Senate Intelligence Committee grilled the nation's top intelligence officials on whether President Trump had invoked executive privilege.

Both the Director of National Intelligence and the Director of the National Security agency declined to answer repeated questions about their conversations with President Trump regarding the on-going Russian investigation.

Throughout the hearing, some of the senators on both sides of the aisle became visibly frustrated when their questions went unanswered.

Maine Senator Angus King repeatedly asked admiral Mike Rogers, the Director of the National Security Agency, if there was any legal basis for their refusal to answer questions.

Dan Coats, the Director of National Intelligence was also repeatedly asked about private conversations he may have had with President Trump.

Both Coats and Rogers said they were still awaiting word from the White House counsel on the issue of executive privilege.

Former FBI director James Comey will finally make his much-anticipated appearance Thursday on Capitol Hill starting at 10 a.m., providing dramatic testimony that President Trump pressed him to pledge his loyalty and drop the investigation of former national security adviser Michael Flynn's ties to Russia.

Watch it live on NEWS CENTER or on our Facebook pages.