WASHINGTON — Brett Kavanaugh stood up for a lunch break, began to button up his jacket and turned around to find the outstretched hand of Fred Guttenberg, whose daughter Jaime was killed in the Parkland mass shooting on Valentine's Day.

Kavanaugh, President Donald Trump's Supreme Court pick, declined to shake it.

"Just walked up to Judge Kavanaugh as the morning session ended," Guttenberg tweeted. "Put out my hand to introduce myself as Jaime Guttenberg's dad. He pulled his hand back, turned his back to me and walked away. I guess he did not want to deal with the reality of gun violence."

The three-second exchange, caught on video by CSPAN, instantly went viral, as Democrats try to muster attacks on Kavanaugh even though they likely don't have the votes to stop his eventual confirmation. The first leg of Kavanaugh's confirmation hearing on Tuesday was frequently interrupted by protesters in the room, with encouragement from Democrats.

The White House said Guttenberg, a vocal advocate for increased gun-control measures who has traveled to Capitol Hill frequently over the last six months to push for changes in legislation, was "an unidentified individual" and that security intervened before Kavanaugh could shake his hand.

"As Judge Kavanaugh left for his lunch break, an unidentified individual approached him," White House deputy press secretary Raj Shah tweeted. "Before the Judge was able to shake his hand, security had intervened."

But the video of the exchange shows Kavanaugh turning around to Guttenberg's outstretched hand with no one in between them. After about three seconds, a security officer approaches Guttenberg from behind and gets between Guttenberg and Kavanaugh, as Kavanaugh begins to walk away.

Guttenberg tweeted he was there as a guest of California Sen. Dianne Feinstein, a Democrat who has authored a bill that would ban assault weapons. He called Shah's interpretation of events "incorrect."

"I was here all day and introduced by Senator Feinstein. No security involved. He turned and walked away," Guttenberg tweeted.

Video of the exchange shows Guttenberg approaching Kavanaugh and Guttenberg saying, "Hi, I'm Fred Guttenberg. My daughter was murdered in Parkland." Kavanaugh began to walk away and Guttenberg raised his voice to finish his sentence.

"You're walking away, have a great day," Guttenberg said after Kavanaugh walked away from him.

According to multiple reports, Democrats huddled over the weekend to discuss ways to oppose Kavanaugh during his hearing, which was broadcast across major TV networks live. Within three hours of Guttenberg's and Kavanaugh's exchange political groups aligned with Democrats were using photos and videos of the incident to run advertisements opposing Kavanaugh's confirmation.

Republicans currently control 50 U.S. Senate seats, though a Republican replacement for late Sen. John McCain is expected to be seated quickly, giving the GOP the potential votes to confirm Kavanaugh by a slim margin.