The U.S. Treasury is finalizing a list of oligarchs close to Vladimir Putin to be penalized under the sanctions passed last year in response to the Kremlin’s election meddling. It’s “expected to amount to a blacklist of Russia’s elite,” per Bloomberg.

The big picture: Two Russian billionaires have been caught up in the Russia probe, while suspicion around other wealthy men with close ties to Putin has deepened in Washington. Here’s a look at the oligarchs already under U.S. sanctions, and the ones who have caught Robert Mueller's eye.

Expand chart Card deck: Axios Visuals. Net worth estimates via Forbes

The state of the oligarchy: Despite Russia’s economic woes, just three countries (the U.S., China and Germany) have more billionaires than Russia’s 96, according to Forbes. Together they are worth about $400 billion dollars — and that sum is growing.

Some of Russia’s richest men rose to prominence before Vladimir Putin came to power, but remaining among Russia’s business elite requires at least tacit support for, and from, the president.

Meanwhile a newer cluster of oligarchs has entered the fray. These are members of Putin’s inner circle, who have capitalized on those bonds to grow their wealth and influence.

The latest: Four U.S. senators are calling on the White House to include Alisher Usmanov, a metals magnate and former Facebook investor worth $15.1 billion, in the next round of sanctions.

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