Robert F. Kennedy Jr.’s running mate, the Silicon Valley investor Nicole Shanahan, said on Wednesday night that she had given another $8 million to their independent presidential campaign as it carries out the expensive endeavor of gaining ballot access across the country and tries to propel Mr. Kennedy onto debate stages.

Ms. Shanahan’s new donation, which she announced at a comedy fund-raiser in Nashville, brings her total contribution to the campaign to $10 million, not including the $4 million she gave to a super PAC backing Mr. Kennedy to help pay for a Super Bowl advertisement early this year. Ms. Shanahan, a lawyer who was formerly married to the Google co-founder Sergey Brin, gave the campaign $2 million shortly after Mr. Kennedy named her as his running mate in March.

After a nod to the media, Ms. Shanahan said, “I think I know what they’re going to say — they’re going to say Bobby only picked me for my money,” a remark that drew laughter from the crowd.

Ms. Shanahan’s comments came near the end of a four-hour event at the storied Ryman Auditorium in Nashville. She followed performances by comedians including Russell Brand, Rob Schneider and Jim Breuer, a former “Saturday Night Live” cast member. Many of the performers praised Mr. Kennedy, but they also used their time onstage to rail against Covid vaccinations, Dr. Anthony S. Fauci, the mainstream news media and President Biden.

Ms. Shanahan’s personal wealth has been a significant asset for Mr. Kennedy. While campaign finance laws constrain individuals from donating more than $6,600 to a campaign, the candidates themselves can give unlimited sums of their own money.

Her cash has provided a financial lifeline as their campaign undertakes a costly effort to get on the ballot in all 50 states — which would be a challenging and expensive undertaking under any circumstances, even more so because the Democratic Party and its allies have pledged to mount legal challenges to the effort.