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“This is the year, in our view, that we are able to demonstrate that you can use climate, you can do it well, you can do it in a smart way, to win political races,” Steyer adviser Chris Lehane told CNN.

Mr. Steyer is scheduled to host a May 28 fundraiser at his San Francisco home featuring Vice President Joe Biden, the billionaire’s second Democratic fundraiser this year. The vice president is appearing at a May 27 fundraiser in Denver for Mr. Udall.

The liberal billionaire is often compared to the industrialist Koch brothers, wealthy campaign donors who support Republican candidates and conservative causes.