House Republicans unveiled a budget proposal Tuesday to reign in the national debt by reshaping Medicare, cutting into programs for the poor and reshuffling the tax code to sharply lower rates. Federal spending would be slashed $5.3 trillion over the next 10 years. Those cuts, along with the tax changes, would put the nation on course to wipe out deficits and balance the budget by 2040. Tea-party conservatives demand Republicans balance the budget in the next 10 years. The proposal calls for wiping out the alternative minimum tax, lowering the 35% tax on corporate profits to 25%, granting U.S. corporations a blanket exemption on profits earned overseas, and replacing the current tax structure’s six brackets with just two: a 10 percent rate for lower-income earners and a 25 percent rate for upper-income earners.