Sen. Bernie Sanders criticized Google co-founder Sergey Brin for spending heavily to oppose California’s proposed billionaire wealth tax. Sanders argued that Brin could afford the one-time levy while still retaining an enormous fortune. Sanders said Brin has gained about $140 billion in wealth since Donald Trump was elected. Under the proposed one-time 5% tax, Sanders estimated Brin could owe roughly $14 billion. Brin has emerged as one of the most prominent opponents of the measure. He has reportedly contributed about $102 million to Building a Better California, a political advocacy group fighting the proposal and supporting pro-business policies. Brin has compared the wealth tax to socialist policies he experienced while growing up in the Soviet Union. He has argued that aggressive taxation could push California toward a more hostile environment for entrepreneurs and wealthy residents. The proposal, known as Proposition 40, is expected to appear on California’s November ballot. It would impose a one-time 5% tax on roughly 200 billionaires, with much of the revenue intended to support the state’s health care system. The debate comes as some wealthy residents and businesses have moved assets or entities out of California. Critics warn that the tax could accelerate that trend and ultimately reduce the state’s tax base. California Gov. Gavin Newsom also opposes the state-level wealth tax. However, he has supported the idea of a federal minimum tax on Americans with more than $100 million in assets, arguing that a national policy would be harder to avoid through relocation.