The super PAC of one of California’s richest political donors, who supports centrist Republicans, has dropped more money on an obscure House race than both candidates combined.

The committee, Spirit of Democracy America is largely funded by Charles T. Munger, Jr., the heir to Berkshire Hathaway’s billionaire vice chairman and the third third biggest donor in California politics in the past decade, according to a study by California Watch. The group has spent more than $545,000 on the race so far. Combined, candidates Paul Cook and Greg Imus reported spending $363,000 as of the most recent ...