Sen. Bernie Sanders on Tuesday proposed an “extreme wealth tax” on the highest-income Americans, along with a “national wealth registry” that he said would help prevent them from avoiding the tax.

The tax rate would start at 1 percent on net worth of more than $32 million and rise with income above that, topping out at 8 percent on wealth over $10 billion.

Sanders’ Democratic presidential campaign said the tax would raise $4.35 trillion over a decade and would be used to fund "Medicare for All", along with his plans for affordable housing and universal childcare.

Several of the other Democratic presidential candidates have proposed slapping additional taxes on the highest-income households. Sanders, an independent from Vermont, had already proposed a major hike in estate taxes and raising the top marginal tax rate on income above $10 million.

Beyond funding programs they have proposed, the candidates say their plans would combat income inequality.

“At a time when millions of people are working two or three jobs to feed their families, the three wealthiest people in this country own more wealth than the bottom half of the American people,” Sanders said in a statement. “Enough is enough. We are going to take on the billionaire class, substantially reduce wealth inequality in America and stop our democracy from turning into a corrupt oligarchy.”

Sanders’ campaign also released a letter by University of California, Berkeley economists Emmanuel Saez and Gabriel Zucman, who said the plan would “fully eliminate the gap between wealth growth for billionaires and wealth growth for the middle class.”

Saez and Zucman have also analyzed Democratic Sen. Elizabeth Warren’s plan for a tax on the wealthiest Americans.

Some other economists, notably former Treasury Secretary Larry Summers, have questioned whether wealth taxes would raise as much as proponents say. The economists cite the difficulty of valuing some of the holdings of high-income individuals and their ability to avoid taxes by exploiting various loopholes in the tax code.

Sanders’ plan includes enforcement measures that he said would block evasion of his proposed tax. In addition to the wealth registry, the IRS would be required to audit all billionaires and 30 percent of wealth tax returns for others paying the highest tax rates.

He also proposed boosting the “exit tax” on Americans who expatriate to avoid taxes, to 40 percent of the net value of all assets under $1 billion and 60 percent above $1 billion.