Meg Whitman, former eBay CEO and current HP CEO, who was once the Republican nominee for Governor in California will campaign for Hillary Clinton in Colorado.
While various GOP leaders have tepidly endorsed Clinton, primarily due to their opposition to Trump, none have so far shown up at events with her except Whitman. In addition to courting unsatisfied traditional Republican voters, Clinton is also trying to appeal to large Republican donors, such as Whitman.
Whitman also served as the co-finance chair for Mitt Romney's 2012 Presidential Campaign. She spent nearly 144 million dollars of her own money on her 2010 California Governor campaign, the most of any candidate in US history. However, she lost in a landslide, 54% to 41% to Governor Jerry Brown.