Since September 1, Kaine has headlined 25 fundraisers in 12 states and Washington, DC, while Clinton has only held eight.
Kaine continued his fundraising blitz on Wednesday in California with multiple events in the Bay Area, including a luncheon featuring two long-time Republican donors. Thursday, he's in Houston for an event that features singer Michael Bolton.
This is Bolton's second fundraiser for Clinton; he appeared at an event during the Democratic primaries.
The Texas Tribune first reported Bolton's appearance.
The Houston event is part of Kaine's cash-raising spree.
Kaine appeared Wednesday at the Atherton home of Jillian Manus, a Republican donor, philanthropist and businesswoman. The event will be co-hosted by HP CEO Meg Whitman, who ran for California governor as a Republican in 2010. Whitman endorsed Clinton in August, writing in a statement that she would vote for and donate to Clinton.
According to average ticket prices and attendance figures provided by the Clinton campaign, Kaine has raised over $16 million in September, as of Wednesday. Clinton has raised around $13 million by the same standard.
Clinton also canceled her trip to California earlier this month after she was diagnosed with pneumonia.
The change comes after an August where both Clinton and Kaine focused more on fundraising than they did on campaigning. The Democratic duo headlined 70 fundraisers in August (37 for Clinton, 33 for Kaine). The events raised over $80 million, according to CNN's estimate.
Clinton aides say that August will be the high-water mark for Clinton personally headlining events. While she will continue to headline events, one aide said more of the load would continue to fall on Kaine.
The change is one that donors have long expected and were somewhat surprised it didn't happen in August.
Even if Clinton was a more prolific fundraiser in August, Kaine hit the ground running on the fundraising circuit after he was named Clinton's running mate in July. To date, the former Virginia senator has headlined 58 fundraising events and raised closed to $30 million.
Clinton still remains a far bigger draw than Kaine, with many of her fundraisers costing tens of thousands of dollars to attend. But Kaine has headlined his share of top dollar fundraisers.
An event at the Los Angeles home of Cynthia and Charles Hirschhorn on Tuesday raised $1.4 million. Charles Hirschhorn, a movie producer who worked on "Bull Durham" and "Dirty Rotten Scoundrels," was housemates with Kaine in their student days at Harvard Law School.
On Monday, Kaine headlined a "Latinos for Hillary" event at the Los Angeles home of actress Eva Longoria.
Kaine also headlined an event Tavern on the Green, the historic New York restaurant in Central Park, where five donors paid a whopping $500,000 to dine with the VP candidate. In all, the intimate event raised $2.5 million.
Kaine, a former chairman of the Democratic National Committee, was tapped as Clinton's running mate, in part, because of his ability to raise the money needed to compete in a presidential election.
While other factors like his preparedness and ability to win over white working-class voters were key factors in Clinton's decision to pick Kaine, aides said in July that the Virginia senator was the best fundraiser being considered.