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The Republican chairman of the House Budget Committee said Sunday that his controversial budget proposal would target high-income Americans, by specifically eliminating deductions and loopholes for the wealthy while leaving "middle-income tax writeoffs" in place.

Democrats have assailed Rep. Paul Ryan's budget plan -- the sequel to last year's proposal -- as a gift to the 1 percent, claiming it would hurt the most vulnerable while padding the pockets of the well-off.

Ryan, though, told "Fox News Sunday" that the plan would close tax breaks for top earners.

"Take away the tax shelter, subject all of their income to taxation, and get more revenue -- and we can lower everybody's tax rate in return," Ryan, R-Wis., said.

The influential lawmaker would not get too deep into specifics about which deductions might be eliminated and which might be spared. He said he wants the tax-focused House Ways and Means Committee to work that out in public.

But Ryan argued that popular deductions might not have to be eliminated for everybody -- just the high-income earners who "disproportionately" use them. He indicated a willingness to end the home mortgage interest deduction and other breaks for top earners.

In exchange, Ryan said he envisions a flatter, simpler tax code. His proposal calls for turning the current six-bracket system into a two-bracket system for individuals -- one rate at 10 percent, the other at 25 percent.

Ryan said it's "impossible" to know whether the wealthy would end up benefiting more or less from all these changes.

The plan calls for $3.3 trillion more in deficit reduction over the next decade as compared against President Obama's plan. The deficit reduction, though, is achieved by spending cuts -- not the balance of spending cuts and tax increases that Democrats say is most fair.

White House senior adviser David Plouffe told "Fox News Sunday" that Ryan's plan "fails the test of balance, fairness and shared responsibility."

"It showers huge tax cuts on millionaires and billionaires, paid for by seniors and veterans," he said, claiming the Ryan plan would give the "average" millionaire a tax cut of $150,000.

And he assailed the plan for "voucherizing Medicare" -- a reference to the proposal to give future Medicare seniors the option to use subsidies to enroll in private plans.

The proposal states the changes would only apply to those under 55.

While Republicans hold a strong majority in the House, the Ryan plan would run into stiff resistance in the Democrat-controlled Senate, and certainly at the White House. Plouffe, though, suggested that Ryan was banking on GOP presidential front-runner Mitt Romney to get the plan passed next year, should Romney win the nomination and the White House.