Democratic Sen. Mark Warner, the vice chairman of the Senate Intelligence Committee, can't figure out why anyone continues to take the Trump administration at its word in the investigation into Russia's interference in the 2016 election.

"I'm not sure why we take anybody in the senior level of the Trump administration at their word," Warner told CNN's "State of the Union" on Sunday.

"There seems to be a convenient pattern where all of the senior officials of the Trump campaign forget about meetings with Russians, don't put it on their forms until evidence comes out and then they have to amend," he continued.

Trump's son-in-law and White House adviser Jared Kushner has amended a federal disclosure form to obtain security clearance three times, adding more than 100 names.

Applicants for security clearances must list all their meetings with foreign contacts.

One of the updates included Kushner's meeting with Russian lawyer Natalia Veselnitskaya. Donald Trump Jr. and Trump campaign chairman Paul Manafort were also present at the meeting in Trump Tower.

"It's unbelievable that neither the son nor son-in-law ever shared that information with their dad, the candidate," Warner said.

The president said last week he wasn't aware of the meeting with the Russian lawyer until the story made headlines.