Democratic Contenders Hoping to Run on Soaking the Rich

In this image from Senate Television, Sen. Elizabeth Warren, D-Mass., speaks on the floor of the U.S. Senate in Washington, Feb. 6, 2017, about the nomination of Betsy DeVos to be Education Secretary. The Senate will be in session around the clock this week as Republicans aim to confirm more of President Donald Trump's Cabinet picks over Democratic opposition. Senate TV via AP

WASHINGTON—The last Democrat to win a presidential election, Barack Obama, ran in 2012 on a platform of raising taxes for top earners to nearly 40 percent. Now a new crop of Democratic presidential hopefuls is signaling that they want to go even further.

Massachusetts Sen. Elizabeth Warren is floating a 2 percent tax on all assets of people with a net worth of more than $50 million—a moon-shot plan that could face legal challenges for hitting investments, homes, and cars, not just income.