Now Playing: Giuliani warns of Mueller 'doing a Comey'

Now Playing: Clock ticking for both sides in court fight over Trump lawyer's documents

Now Playing: WH: 'There's still cause for concern' regarding Trump's spy claims

Now Playing: Kim Kardashian West visits White House to discuss clemency case

Now Playing: White House responds to 'spygate' claims, 'Roseanne' cancellation

Now Playing: Boy asks school safety question during White House press briefing

Now Playing: Michael Cohen's legal team racing to review materials seized in FBI raids

Now Playing: Prosecutor rebukes former Missouri governor, then drops felony case against him

Now Playing: Boy tries to hug Trump, gets kiss on forehead too

Now Playing: Top Republican debunks Trump's 'spy' claims

Now Playing: Trump repeats unsubstantiated spy claim at GOP rally

Now Playing: Trump says Mexico will pay for border wall and 'enjoy it'

Now Playing: Trump returns to campaign mode in Tennessee ahead of midterms

Now Playing: Embattled Missouri Gov. Eric Greitens resigns from office

Now Playing: Former head of NK spy agency reportedly bound for US, meeting with Pompeo

Now Playing: Freshman Republican congressman decides to retire, citing alcoholism

Now Playing: Trump slammed for Memorial Day tweet

Now Playing: Sen. Elizabeth Warren talks immigration, 'spygate' conspiracy, North Korea summit

Now Playing: Ivanka Trump posts photo with son amid reports of missing children

Now Playing: GOP lawmaker to retire: 'I'm an alcoholic'