Robert F. Kennedy Jr.'s running mate, Nicole Shanahan, made a significant donation to his underdog campaign for the White House one day after he announced his vice presidential pick last month.

Shanahan, a wealthy lawyer and entrepreneur, officially joined the Kennedy ticket in Oakland, California, on March 26. The next day, she donated $2 million to the campaign, according to Kennedy's latest Federal Election Commission filing. She had previously donated a smaller amount to Kennedy's campaign, but because she is now a candidate on the ticket, she can spend unlimited amounts of her own money on the effort.