Senate Democrats target billionaires

• The approach could face constitutional challenges and logistical ones.

The details: Senate Finance Chair Ron Wyden (D-Ore.) next week will unveil a tax on the unrealized capital gains of the ultra-wealthy, Bloomberg reports:

• "The proposal ... would set the so-called billionaires' income tax at $1 billion in annual income, or three consecutive years of $100 million or more in income — hitting some 700 taxpayers."

Between the lines: The Washington Post points out this approach "would shield not only the lower and middle classes but also exempt the bulk of the top 1 percent — concentrating the higher rates instead on the wealthiest 0.0002 percent."

The intrigue: Sen. Mark Warner (D-Va.), a member of the Finance Committee, was saying all week that senators should slow down.

• "There's a reason why you only do tax policy in a major way every few years — it's really complicated," Warner told Axios.
• "My fear is if we're going to try some innovative new ideas and if we don't have time to develop them ... we could mess some of this up."