Where would all the money come from? For the most part, the rich. Van Hollen is proposing to scrap tax breaks that go disproportionately to the wealthy and to add a new tax on stock trades that he is dubbing "a high roller fee." The latter tax could hit anyone who is active in the stock market, but Van Hollen argues it would only really effect wealthy high-frequency traders. "We must ensure that all Americans who work hard and play by the rules are rewarded with a fair share of a growing economic pie," he said in a speech laying out his plan in Washington.

The plan drew swift endorsements from Nancy Pelosi, the House Democratic leader, and an array of liberal groups, although not yet from the White House. While the tax cut for the middle class should be an easy political sell (Who doesn't want an extra $1,000-2,000?), the more punitive Wall Street policies are significant because they put the Democratic leadership behind ideas that have energized the Elizabeth Warren wing of the party. A group supportive of Warren, the Progressive Change Campaign Committee, applauded Van Hollen for his plan "taxing high-risk Wall Street gambling." "Since Election Day, we've been urging the Democratic Party to rally around big economic populist ideas that impact millions of people's lives," the PCCC said.

Republicans, as expected, trashed the proposal. "Just as the sun rises in the east, Washington Democrats propose another massive tax increase," said Brendan Buck, a spokesman for Representative Paul Ryan, who announced on Monday he would forgo running for president to focus on writing tax policy as chairman of the House Ways and Means Committee. "Here in the House," Buck said, "our focus is going to be on cleaning up the tax code so that we can lower rates for all taxpayers and help create good-paying jobs, not scaring them off with punitive tax hikes."

With the GOP firmly in control of Congress for the next two years, Van Hollen's proposal has no chance of going anywhere immediately. But it lays down a marker for Republicans, who have talked increasingly about wanting to move away from their budget-slashing reputation and toward policies that can win over the prized middle class. And it can also be seen as an offering to Hillary Clinton, who will need a platform to run on in 2016 as well as a way of attracting the liberals who are disappointed that the more populist Warren won't challenge her. So while it won't become law, Van Hollen's plan is likely to help shape the economic debate both in Congress and on the campaign trail.

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