Rep. Ro Khanna calls on RFK Jr.'s running mate to step down. Here's how Nicole Shanahan responded.

Democratic Rep. Ro Khanna of California called on Nicole Shanahan, the running mate of presidential candidate Robert F. Kennedy, to step down, warning that supporting Kennedy could pave the way for former President Donald Trump to win the election. 

He made his pitch to her in a letter he shared with CBS News, though he hadn't yet sent it to Shanahan. 

"Even Trump himself, and other members of his team, have admitted that a RFK Jr. ticket will help his reelection," Khanna wrote in his letter.